diff --git a/dlt-connector/src/data/Transaction.logic.test.ts b/dlt-connector/src/data/Transaction.logic.test.ts
new file mode 100644
index 000000000..c652fe794
--- /dev/null
+++ b/dlt-connector/src/data/Transaction.logic.test.ts
@@ -0,0 +1,323 @@
+import { Community } from '@entity/Community'
+import { Transaction } from '@entity/Transaction'
+import { Decimal } from 'decimal.js-light'
+
+import { logger } from '@/logging/logger'
+
+import { CommunityRoot } from './proto/3_3/CommunityRoot'
+import { CrossGroupType } from './proto/3_3/enum/CrossGroupType'
+import { GradidoTransfer } from './proto/3_3/GradidoTransfer'
+import { RegisterAddress } from './proto/3_3/RegisterAddress'
+import { TransactionBody } from './proto/3_3/TransactionBody'
+import { TransactionLogic } from './Transaction.logic'
+import { GradidoCreation } from './proto/3_3/GradidoCreation'
+import { GradidoDeferredTransfer } from './proto/3_3/GradidoDeferredTransfer'
+
+let a: Transaction
+let b: Transaction
+
+describe('data/transaction.logic', () => {
+  describe('isBelongTogether', () => {
+    beforeEach(() => {
+      const now = new Date()
+      let body = new TransactionBody()
+      body.type = CrossGroupType.OUTBOUND
+      body.transfer = new GradidoTransfer()
+      body.otherGroup = 'recipient group'
+
+      a = new Transaction()
+      a.community = new Community()
+      a.communityId = 1
+      a.otherCommunityId = 2
+      a.id = 1
+      a.signingAccountId = 1
+      a.recipientAccountId = 2
+      a.createdAt = now
+      a.amount = new Decimal('100')
+      a.signature = Buffer.alloc(64)
+      a.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+
+      body = new TransactionBody()
+      body.type = CrossGroupType.INBOUND
+      body.transfer = new GradidoTransfer()
+      body.otherGroup = 'sending group'
+
+      b = new Transaction()
+      b.community = new Community()
+      b.communityId = 1
+      b.otherCommunityId = 2
+      b.id = 2
+      b.signingAccountId = 1
+      b.recipientAccountId = 2
+      b.createdAt = now
+      b.amount = new Decimal('100')
+      b.signature = Buffer.alloc(64)
+      b.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+    })
+
+    const spy = jest.spyOn(logger, 'info')
+
+    it('true', () => {
+      const logic = new TransactionLogic(a)
+      expect(logic.isBelongTogether(b)).toBe(true)
+    })
+
+    it('false because of same id', () => {
+      b.id = 1
+      const logic = new TransactionLogic(a)
+      expect(logic.isBelongTogether(b)).toBe(false)
+      expect(spy).toHaveBeenLastCalledWith('id is the same, it is the same transaction!')
+    })
+
+    it('false because of different signing accounts', () => {
+      b.signingAccountId = 17
+      const logic = new TransactionLogic(a)
+      expect(logic.isBelongTogether(b)).toBe(false)
+      expect(spy).toHaveBeenLastCalledWith(
+        'transaction a and b are not pairs',
+        expect.objectContaining({}),
+      )
+    })
+
+    it('false because of different recipient accounts', () => {
+      b.recipientAccountId = 21
+      const logic = new TransactionLogic(a)
+      expect(logic.isBelongTogether(b)).toBe(false)
+      expect(spy).toHaveBeenLastCalledWith(
+        'transaction a and b are not pairs',
+        expect.objectContaining({}),
+      )
+    })
+
+    it('false because of different community ids', () => {
+      b.communityId = 6
+      const logic = new TransactionLogic(a)
+      expect(logic.isBelongTogether(b)).toBe(false)
+      expect(spy).toHaveBeenLastCalledWith(
+        'transaction a and b are not pairs',
+        expect.objectContaining({}),
+      )
+    })
+
+    it('false because of different other community ids', () => {
+      b.otherCommunityId = 3
+      const logic = new TransactionLogic(a)
+      expect(logic.isBelongTogether(b)).toBe(false)
+      expect(spy).toHaveBeenLastCalledWith(
+        'transaction a and b are not pairs',
+        expect.objectContaining({}),
+      )
+    })
+
+    it('false because of different createdAt', () => {
+      b.createdAt = new Date('2021-01-01T17:12')
+      const logic = new TransactionLogic(a)
+      expect(logic.isBelongTogether(b)).toBe(false)
+      expect(spy).toHaveBeenLastCalledWith(
+        'transaction a and b are not pairs',
+        expect.objectContaining({}),
+      )
+    })
+
+    describe('false because of mismatching cross group type', () => {
+      const body = new TransactionBody()
+      it('a is LOCAL', () => {
+        body.type = CrossGroupType.LOCAL
+        a.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        const logic = new TransactionLogic(a)
+        expect(logic.isBelongTogether(b)).toBe(false)
+        expect(spy).toHaveBeenNthCalledWith(7, 'no one can be LOCAL')
+        expect(spy).toHaveBeenLastCalledWith(
+          "cross group types don't match",
+          expect.objectContaining({}),
+        )
+      })
+
+      it('b is LOCAL', () => {
+        body.type = CrossGroupType.LOCAL
+        b.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        const logic = new TransactionLogic(a)
+        expect(logic.isBelongTogether(b)).toBe(false)
+        expect(spy).toHaveBeenNthCalledWith(9, 'no one can be LOCAL')
+        expect(spy).toHaveBeenLastCalledWith(
+          "cross group types don't match",
+          expect.objectContaining({}),
+        )
+      })
+
+      it('both are INBOUND', () => {
+        body.type = CrossGroupType.INBOUND
+        a.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        b.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        const logic = new TransactionLogic(a)
+        expect(logic.isBelongTogether(b)).toBe(false)
+        expect(spy).toHaveBeenLastCalledWith(
+          "cross group types don't match",
+          expect.objectContaining({}),
+        )
+      })
+
+      it('both are OUTBOUND', () => {
+        body.type = CrossGroupType.OUTBOUND
+        a.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        b.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        const logic = new TransactionLogic(a)
+        expect(logic.isBelongTogether(b)).toBe(false)
+        expect(spy).toHaveBeenLastCalledWith(
+          "cross group types don't match",
+          expect.objectContaining({}),
+        )
+      })
+
+      it('a is CROSS', () => {
+        body.type = CrossGroupType.CROSS
+        a.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        const logic = new TransactionLogic(a)
+        expect(logic.isBelongTogether(b)).toBe(false)
+        expect(spy).toHaveBeenLastCalledWith(
+          "cross group types don't match",
+          expect.objectContaining({}),
+        )
+      })
+
+      it('b is CROSS', () => {
+        body.type = CrossGroupType.CROSS
+        b.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        const logic = new TransactionLogic(a)
+        expect(logic.isBelongTogether(b)).toBe(false)
+        expect(spy).toHaveBeenLastCalledWith(
+          "cross group types don't match",
+          expect.objectContaining({}),
+        )
+      })
+
+      it('true with a as INBOUND and b as OUTBOUND', () => {
+        let body = TransactionBody.fromBodyBytes(a.bodyBytes)
+        body.type = CrossGroupType.INBOUND
+        a.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        body = TransactionBody.fromBodyBytes(b.bodyBytes)
+        body.type = CrossGroupType.OUTBOUND
+        b.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        const logic = new TransactionLogic(a)
+        expect(logic.isBelongTogether(b)).toBe(true)
+      })
+    })
+
+    describe('false because of transaction type not suitable for cross group transactions', () => {
+      const body = new TransactionBody()
+      body.type = CrossGroupType.OUTBOUND
+      it('without transaction type (broken TransactionBody)', () => {
+        a.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        const logic = new TransactionLogic(a)
+        expect(() => logic.isBelongTogether(b)).toThrowError("couldn't determine transaction type")
+      })
+
+      it('not the same transaction types', () => {
+        const body = new TransactionBody()
+        body.type = CrossGroupType.OUTBOUND
+        body.registerAddress = new RegisterAddress()
+        a.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        const logic = new TransactionLogic(a)
+        expect(logic.isBelongTogether(b)).toBe(false)
+        expect(spy).toHaveBeenLastCalledWith(
+          "transaction types don't match",
+          expect.objectContaining({}),
+        )
+      })
+
+      it('community root cannot be a cross group transaction', () => {
+        let body = new TransactionBody()
+        body.type = CrossGroupType.OUTBOUND
+        body.communityRoot = new CommunityRoot()
+        a.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        body = new TransactionBody()
+        body.type = CrossGroupType.INBOUND
+        body.communityRoot = new CommunityRoot()
+        b.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        const logic = new TransactionLogic(a)
+        expect(logic.isBelongTogether(b)).toBe(false)
+        expect(spy).toHaveBeenLastCalledWith(
+          "TransactionType COMMUNITY_ROOT couldn't be a CrossGroup Transaction",
+        )
+      })
+
+      it('Gradido Creation cannot be a cross group transaction', () => {
+        let body = new TransactionBody()
+        body.type = CrossGroupType.OUTBOUND
+        body.creation = new GradidoCreation()
+        a.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        body = new TransactionBody()
+        body.type = CrossGroupType.INBOUND
+        body.creation = new GradidoCreation()
+        b.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        const logic = new TransactionLogic(a)
+        expect(logic.isBelongTogether(b)).toBe(false)
+        expect(spy).toHaveBeenLastCalledWith(
+          "TransactionType GRADIDO_CREATION couldn't be a CrossGroup Transaction",
+        )
+      })
+
+      it('Deferred Transfer cannot be a cross group transaction', () => {
+        let body = new TransactionBody()
+        body.type = CrossGroupType.OUTBOUND
+        body.deferredTransfer = new GradidoDeferredTransfer()
+        a.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        body = new TransactionBody()
+        body.type = CrossGroupType.INBOUND
+        body.deferredTransfer = new GradidoDeferredTransfer()
+        b.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+        const logic = new TransactionLogic(a)
+        expect(logic.isBelongTogether(b)).toBe(false)
+        expect(spy).toHaveBeenLastCalledWith(
+          "TransactionType GRADIDO_DEFERRED_TRANSFER couldn't be a CrossGroup Transaction",
+        )
+      })
+    })
+
+    describe('false because of wrong amount', () => {
+      it('amount missing on a', () => {
+        a.amount = undefined
+        const logic = new TransactionLogic(a)
+        expect(logic.isBelongTogether(b)).toBe(false)
+        expect(spy).toHaveBeenLastCalledWith('missing amount')
+      })
+
+      it('amount missing on b', () => {
+        b.amount = undefined
+        const logic = new TransactionLogic(a)
+        expect(logic.isBelongTogether(b)).toBe(false)
+        expect(spy).toHaveBeenLastCalledWith('missing amount')
+      })
+
+      it('amount not the same', () => {
+        a.amount = new Decimal('101')
+        const logic = new TransactionLogic(a)
+        expect(logic.isBelongTogether(b)).toBe(false)
+        expect(spy).toHaveBeenLastCalledWith('amounts mismatch', expect.objectContaining({}))
+      })
+    })
+
+    it('false because otherGroup are the same', () => {
+      const body = new TransactionBody()
+      body.type = CrossGroupType.OUTBOUND
+      body.transfer = new GradidoTransfer()
+      body.otherGroup = 'sending group'
+      a.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+      const logic = new TransactionLogic(a)
+      expect(logic.isBelongTogether(b)).toBe(false)
+      expect(spy).toHaveBeenLastCalledWith('otherGroups are the same', expect.objectContaining({}))
+    })
+
+    it('false because of different memos', () => {
+      const body = new TransactionBody()
+      body.type = CrossGroupType.OUTBOUND
+      body.transfer = new GradidoTransfer()
+      body.otherGroup = 'recipient group'
+      body.memo = 'changed memo'
+      a.bodyBytes = Buffer.from(TransactionBody.encode(body).finish())
+      const logic = new TransactionLogic(a)
+      expect(logic.isBelongTogether(b)).toBe(false)
+      expect(spy).toHaveBeenLastCalledWith('memo differ', expect.objectContaining({}))
+    })
+  })
+})
diff --git a/dlt-connector/src/data/Transaction.logic.ts b/dlt-connector/src/data/Transaction.logic.ts
index 9ca6330ba..f237e9b3b 100644
--- a/dlt-connector/src/data/Transaction.logic.ts
+++ b/dlt-connector/src/data/Transaction.logic.ts
@@ -83,30 +83,26 @@ export class TransactionLogic {
       this.self.recipientAccountId !== otherTransaction.recipientAccountId ||
       this.self.communityId !== otherTransaction.communityId ||
       this.self.otherCommunityId !== otherTransaction.otherCommunityId ||
-      this.self.accountBalanceOnCreation !== otherTransaction.accountBalanceOnCreation ||
       this.self.createdAt.getTime() !== otherTransaction.createdAt.getTime()
     ) {
-      logger.debug('transaction a and b are not pairs', {
-        a: new TransactionLoggingView(this.self),
-        b: new TransactionLoggingView(otherTransaction),
+      logger.info('transaction a and b are not pairs', {
+        a: new TransactionLoggingView(this.self).toJSON(),
+        b: new TransactionLoggingView(otherTransaction).toJSON(),
       })
       return false
     }
     const body = this.getBody()
     const otherBody = TransactionBody.fromBodyBytes(otherTransaction.bodyBytes)
     /**
-     * both can be Cross
+     * both must be Cross or
      * one can be OUTBOUND and one can be INBOUND
      * no one can be LOCAL
      */
-    if (
-      (body.type === otherBody.type && body.type !== CrossGroupType.CROSS) ||
-      body.type === CrossGroupType.LOCAL ||
-      otherBody.type === CrossGroupType.LOCAL
-    ) {
+
+    if (!this.validCrossGroupTypes(body.type, otherBody.type)) {
       logger.info("cross group types don't match", {
-        a: new TransactionBodyLoggingView(body),
-        b: new TransactionBodyLoggingView(otherBody),
+        a: new TransactionBodyLoggingView(body).toJSON(),
+        b: new TransactionBodyLoggingView(otherBody).toJSON(),
       })
       return false
     }
@@ -114,14 +110,14 @@ export class TransactionLogic {
     const otherType = otherBody.getTransactionType()
     if (!type || !otherType) {
       throw new LogError("couldn't determine transaction type", {
-        a: new TransactionBodyLoggingView(body),
-        b: new TransactionBodyLoggingView(otherBody),
+        a: new TransactionBodyLoggingView(body).toJSON(),
+        b: new TransactionBodyLoggingView(otherBody).toJSON(),
       })
     }
     if (type !== otherType) {
       logger.info("transaction types don't match", {
-        a: new TransactionBodyLoggingView(body),
-        b: new TransactionBodyLoggingView(otherBody),
+        a: new TransactionBodyLoggingView(body).toJSON(),
+        b: new TransactionBodyLoggingView(otherBody).toJSON(),
       })
       return false
     }
@@ -132,7 +128,7 @@ export class TransactionLogic {
         TransactionType.GRADIDO_DEFERRED_TRANSFER,
       ].includes(type)
     ) {
-      logger.info(`TransactionType ${type} couldn't be a CrossGroup Transaction`)
+      logger.info(`TransactionType ${TransactionType[type]} couldn't be a CrossGroup Transaction`)
       return false
     }
     if (
@@ -156,21 +152,45 @@ export class TransactionLogic {
     }
     if (body.otherGroup === otherBody.otherGroup) {
       logger.info('otherGroups are the same', {
-        a: new TransactionBodyLoggingView(body),
-        b: new TransactionBodyLoggingView(otherBody),
+        a: new TransactionBodyLoggingView(body).toJSON(),
+        b: new TransactionBodyLoggingView(otherBody).toJSON(),
       })
       return false
     }
     if (body.memo !== otherBody.memo) {
       logger.info('memo differ', {
-        a: new TransactionBodyLoggingView(body),
-        b: new TransactionBodyLoggingView(otherBody),
+        a: new TransactionBodyLoggingView(body).toJSON(),
+        b: new TransactionBodyLoggingView(otherBody).toJSON(),
       })
       return false
     }
     return true
   }
 
+  /**
+   * both must be CROSS or
+   * one can be OUTBOUND and one can be INBOUND
+   * no one can be LOCAL
+   * @return true if crossGroupTypes are valid
+   */
+  protected validCrossGroupTypes(a: CrossGroupType, b: CrossGroupType): boolean {
+    logger.debug('compare ', {
+      a: CrossGroupType[a],
+      b: CrossGroupType[b],
+    })
+    if (a === CrossGroupType.LOCAL || b === CrossGroupType.LOCAL) {
+      logger.info('no one can be LOCAL')
+      return false
+    }
+    if (
+      (a === CrossGroupType.INBOUND && b === CrossGroupType.OUTBOUND) ||
+      (a === CrossGroupType.OUTBOUND && b === CrossGroupType.INBOUND)
+    ) {
+      return true // One can be INBOUND and one can be OUTBOUND
+    }
+    return a === CrossGroupType.CROSS && b === CrossGroupType.CROSS
+  }
+
   public getBody(): TransactionBody {
     if (!this.transactionBody) {
       this.transactionBody = TransactionBody.fromBodyBytes(this.self.bodyBytes)