diff --git a/domain/miningmanager/mempool/mempool_utxo_set.go b/domain/miningmanager/mempool/mempool_utxo_set.go
index 79d793a9a..be8233bec 100644
--- a/domain/miningmanager/mempool/mempool_utxo_set.go
+++ b/domain/miningmanager/mempool/mempool_utxo_set.go
@@ -3,8 +3,6 @@ package mempool
 import (
 	"fmt"
 
-	"github.com/kaspanet/kaspad/domain/consensus/utils/consensushashing"
-
 	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
 	"github.com/kaspanet/kaspad/domain/consensus/utils/utxo"
 	"github.com/kaspanet/kaspad/domain/miningmanager/mempool/model"
@@ -24,23 +22,6 @@ func newMempoolUTXOSet(mp *mempool) *mempoolUTXOSet {
 	}
 }
 
-func (mpus *mempoolUTXOSet) getParentsInPool(transaction *externalapi.DomainTransaction) model.ParentUTXOsInPool {
-	parentsInPool := model.ParentUTXOsInPool{}
-
-	outpoint := &externalapi.DomainOutpoint{
-		TransactionID: *consensushashing.TransactionID(transaction),
-	}
-	for i := range transaction.Inputs {
-		outpoint.Index = uint32(i)
-		utxo, ok := mpus.poolUnspentOutputs[*outpoint]
-		if ok {
-			parentsInPool.Set(i, utxo)
-		}
-	}
-
-	return parentsInPool
-}
-
 func (mpus *mempoolUTXOSet) addTransaction(transaction *model.MempoolTransaction) {
 	outpoint := &externalapi.DomainOutpoint{TransactionID: *transaction.TransactionID()}
 
@@ -65,7 +46,7 @@ func (mpus *mempoolUTXOSet) removeTransaction(transaction *model.MempoolTransact
 		delete(mpus.transactionsByPreviousOutpoint, input.PreviousOutpoint)
 	}
 
-	outpoint := &externalapi.DomainOutpoint{TransactionID: *transaction.TransactionID()}
+	outpoint := externalapi.DomainOutpoint{TransactionID: *transaction.TransactionID()}
 	for i := range transaction.Transaction.Outputs {
 		outpoint.Index = uint32(i)
 
diff --git a/domain/miningmanager/mempool/model/mempool_transaction.go b/domain/miningmanager/mempool/model/mempool_transaction.go
index 9ec2a364e..e89fda409 100644
--- a/domain/miningmanager/mempool/model/mempool_transaction.go
+++ b/domain/miningmanager/mempool/model/mempool_transaction.go
@@ -7,10 +7,10 @@ import (
 
 // MempoolTransaction represents a transaction inside the main TransactionPool
 type MempoolTransaction struct {
-	Transaction     *externalapi.DomainTransaction
-	ParentsInPool   ParentUTXOsInPool
-	IsHighPriority  bool
-	AddedAtDAAScore uint64
+	Transaction              *externalapi.DomainTransaction
+	ParentTransactionsInPool OutpointToTransaction
+	IsHighPriority           bool
+	AddedAtDAAScore          uint64
 }
 
 // TransactionID returns the ID of this MempoolTransaction
diff --git a/domain/miningmanager/mempool/model/parent_utxos_in_pool.go b/domain/miningmanager/mempool/model/parent_utxos_in_pool.go
deleted file mode 100644
index c17f149ce..000000000
--- a/domain/miningmanager/mempool/model/parent_utxos_in_pool.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package model
-
-import "github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
-
-// ParentUTXOsInPool represent the utxos a transaction spends out of the mempool.
-// The utxos are indexed by transaction output index, for convenient access.
-type ParentUTXOsInPool map[int]externalapi.UTXOEntry
-
-func (pip ParentUTXOsInPool) Get(index int) (externalapi.UTXOEntry, bool) {
-	utxoEntry, ok := pip[index]
-	return utxoEntry, ok
-}
-
-func (pip ParentUTXOsInPool) Set(index int, utxoEntry externalapi.UTXOEntry) {
-	pip[index] = utxoEntry
-}
diff --git a/domain/miningmanager/mempool/orphan_pool.go b/domain/miningmanager/mempool/orphan_pool.go
index 02491984a..ae8f77f0d 100644
--- a/domain/miningmanager/mempool/orphan_pool.go
+++ b/domain/miningmanager/mempool/orphan_pool.go
@@ -146,10 +146,10 @@ func (op *orphansPool) unorphanTransaction(orphanTransaction *model.MempoolTrans
 		return nil, err
 	}
 	mempoolTransaction := &model.MempoolTransaction{
-		Transaction:     orphanTransaction.Transaction,
-		ParentsInPool:   op.mempool.mempoolUTXOSet.getParentsInPool(orphanTransaction.Transaction),
-		IsHighPriority:  false,
-		AddedAtDAAScore: virtualDAAScore,
+		Transaction:              orphanTransaction.Transaction,
+		ParentTransactionsInPool: op.mempool.transactionsPool.getParentTransactionsInPool(orphanTransaction.Transaction),
+		IsHighPriority:           false,
+		AddedAtDAAScore:          virtualDAAScore,
 	}
 	err = op.mempool.transactionsPool.addMempoolTransaction(mempoolTransaction)
 	if err != nil {
@@ -165,7 +165,7 @@ func (op *orphansPool) removeOrphan(orphanTransactionID *externalapi.DomainTrans
 		return nil
 	}
 
-	delete(op.allOrphans, orphanTransactionID)
+	delete(op.allOrphans, *orphanTransactionID)
 
 	for i, input := range orphanTransaction.Transaction.Inputs {
 		orphans, ok := op.orphansByPreviousOutpoint[input.PreviousOutpoint]
diff --git a/domain/miningmanager/mempool/transactions_pool.go b/domain/miningmanager/mempool/transactions_pool.go
index 5f1a239ba..3aca75769 100644
--- a/domain/miningmanager/mempool/transactions_pool.go
+++ b/domain/miningmanager/mempool/transactions_pool.go
@@ -25,12 +25,43 @@ func newTransactionsPool(mp *mempool) *transactionsPool {
 	}
 }
 
-func (tp *transactionsPool) addTransaction(transaction *externalapi.DomainTransaction, parentsInPool []*model.MempoolTransaction) error {
-	panic("transactionsPool.addTransaction not implemented") // TODO (Mike)
+func (tp *transactionsPool) addTransaction(transaction *externalapi.DomainTransaction,
+	parentTransactionsInPool model.OutpointToTransaction, isHighPriority bool) error {
+
+	virtualDAAScore, err := tp.mempool.virtualDAAScore()
+	if err != nil {
+		return err
+	}
+
+	mempoolTransaction := &model.MempoolTransaction{
+		Transaction:              transaction,
+		ParentTransactionsInPool: parentTransactionsInPool,
+		IsHighPriority:           isHighPriority,
+		AddedAtDAAScore:          virtualDAAScore,
+	}
+
+	return tp.addMempoolTransaction(mempoolTransaction)
 }
 
 func (tp *transactionsPool) addMempoolTransaction(transaction *model.MempoolTransaction) error {
-	panic("transactionsPool.addMempoolTransaction not implemented") // TODO (Mike)
+	tp.allTransactions[*transaction.TransactionID()] = transaction
+
+	for outpoint, parentTransactionInPool := range transaction.ParentTransactionsInPool {
+		tp.chainedTransactionsByPreviousOutpoint[outpoint] = parentTransactionInPool
+	}
+
+	tp.mempool.mempoolUTXOSet.addTransaction(transaction)
+
+	err := tp.transactionsByFeeRate.Push(transaction)
+	if err != nil {
+		return err
+	}
+
+	if transaction.IsHighPriority {
+		tp.highPriorityTransactions[*transaction.TransactionID()] = transaction
+	}
+
+	return nil
 }
 
 func (tp *transactionsPool) expireOldTransactions() error {
@@ -66,10 +97,23 @@ func (tp *transactionsPool) allReadyTransactions() []*externalapi.DomainTransact
 	result := []*externalapi.DomainTransaction{}
 
 	for _, mempoolTransaction := range tp.allTransactions {
-		if len(mempoolTransaction.ParentsInPool) == 0 {
+		if len(mempoolTransaction.ParentTransactionsInPool) == 0 {
 			result = append(result, mempoolTransaction.Transaction)
 		}
 	}
 
 	return result
 }
+
+func (tp *transactionsPool) getParentTransactionsInPool(
+	transaction *externalapi.DomainTransaction) model.OutpointToTransaction {
+
+	parentsTransactionsInPool := model.OutpointToTransaction{}
+
+	for _, input := range transaction.Inputs {
+		transaction := tp.allTransactions[input.PreviousOutpoint.TransactionID]
+		parentsTransactionsInPool[input.PreviousOutpoint] = transaction
+	}
+
+	return parentsTransactionsInPool
+}