wallet: Show alternate wtxids in gettransaction

diff --git a/src/wallet/rpc/transactions.cpp b/src/wallet/rpc/transactions.cpp
index 635f150b..d8535694 100644
--- a/src/wallet/rpc/transactions.cpp
+++ b/src/wallet/rpc/transactions.cpp
@@ -38,6 +38,12 @@ static void WalletTxToJSON(const CWallet& wallet, const CWalletTx& wtx, UniValue
     }
     entry.pushKV("txid", wtx.GetHash().GetHex());
     entry.pushKV("wtxid", wtx.GetWitnessHash().GetHex());
+    UniValue alternate_wtxids(UniValue::VARR);
+    for (const auto& [wtxid, _] : wtx.GetTxs()) {
+        if (wtxid == wtx.GetWitnessHash()) continue;
+        alternate_wtxids.push_back(wtxid.GetHex());
+    }
+    entry.pushKV("alternate_wtxids", alternate_wtxids);
     UniValue conflicts(UniValue::VARR);
     for (const Txid& conflict : wallet.GetTxConflicts(wtx))
         conflicts.push_back(conflict.GetHex());
@@ -395,6 +401,10 @@ static std::vector<RPCResult> TransactionDescriptionString()
            {RPCResult::Type::NUM_TIME, "blocktime", /*optional=*/true, "The block time expressed in " + UNIX_EPOCH_TIME + "."},
            {RPCResult::Type::STR_HEX, "txid", "The transaction id."},
            {RPCResult::Type::STR_HEX, "wtxid", "The hash of serialized transaction, including witness data."},
+           {RPCResult::Type::ARR, "alternate_wtxids", "The wtxids of transactions with different witness data but the same txid.",
+           {
+               {RPCResult::Type::STR_HEX, "wtxid", "The witness transaction id."},
+           }},
            {RPCResult::Type::ARR, "walletconflicts", "Confirmed transactions that have been detected by the wallet to conflict with this transaction.",
            {
                {RPCResult::Type::STR_HEX, "txid", "The transaction id."},
diff --git a/test/functional/wallet_basic.py b/test/functional/wallet_basic.py
index e2ec2cfa..ea95daa2 100755
--- a/test/functional/wallet_basic.py
+++ b/test/functional/wallet_basic.py
@@ -563,7 +563,8 @@ class WalletTest(BitcoinTestFramework):
                                  "category": baz["category"],
                                  "vout":     baz["vout"]}
         expected_fields = frozenset({'amount', 'confirmations', 'details', 'fee',
-                                     'hex', 'lastprocessedblock', 'time', 'timereceived', 'trusted', 'txid', 'wtxid', 'walletconflicts', 'mempoolconflicts'})
+                                     'hex', 'lastprocessedblock', 'time', 'timereceived', 'trusted', 'txid', 'wtxid', 'walletconflicts', 'mempoolconflicts',
+                                     'alternate_wtxids'})
         verbose_field = "decoded"
         expected_verbose_fields = expected_fields | {verbose_field}
 
diff --git a/test/functional/wallet_migration.py b/test/functional/wallet_migration.py
index 50d44c22..093fc886 100755
--- a/test/functional/wallet_migration.py
+++ b/test/functional/wallet_migration.py
@@ -184,13 +184,13 @@ class WalletMigrationTest(BitcoinTestFramework):
         return migrate_info, wallet
 
     def test_basic(self):
-        # Remove the deprecated response fields that'd be present in the RPC responses
-        # sent by the old node(s).
-        def remove_deprecated_keys(list):
+        # Update listtransctions' output from old nodes to be compatible
+        def listtransactions_compatibility(list):
             deprecated_keys = {"bip125-replaceable"}
             for obj in list:
                 for key in deprecated_keys:
                     obj.pop(key)
+                obj["alternate_wtxids"] = []
             return list
 
         default = self.master_node.get_wallet_rpc(self.default_wallet_name)
@@ -248,7 +248,7 @@ class WalletMigrationTest(BitcoinTestFramework):
 
         basic1_migrate, basic1 = self.migrate_and_get_rpc("basic1")
         assert_equal(basic1.getbalance(), bal)
-        self.assert_list_txs_equal(basic1.listtransactions(), remove_deprecated_keys(txs))
+        self.assert_list_txs_equal(basic1.listtransactions(), listtransactions_compatibility(txs))
 
         self.log.info("Test backup file can be successfully restored")
         self.old_node.restorewallet("basic1_restored", basic1_migrate['backup_path'])
@@ -256,7 +256,7 @@ class WalletMigrationTest(BitcoinTestFramework):
         basic1_restored_wi = basic1_restored.getwalletinfo()
         assert_equal(basic1_restored_wi['balance'], bal)
         assert_equal(basic1_restored.listaddressgroupings(), addr_gps)
-        self.assert_list_txs_equal(remove_deprecated_keys(basic1_restored.listtransactions()), txs)
+        self.assert_list_txs_equal(listtransactions_compatibility(basic1_restored.listtransactions()), txs)
 
         # restart master node and verify that everything is still there
         self.restart_node(0)
@@ -286,7 +286,7 @@ class WalletMigrationTest(BitcoinTestFramework):
         # Now migrate and test that we still have the same balance/transactions
         _, basic2 = self.migrate_and_get_rpc("basic2")
         assert_equal(basic2.getbalance(), basic2_balance)
-        self.assert_list_txs_equal(basic2.listtransactions(), remove_deprecated_keys(basic2_txs))
+        self.assert_list_txs_equal(basic2.listtransactions(), listtransactions_compatibility(basic2_txs))
 
         # Now test migration on a descriptor wallet
         self.log.info("Test \"nothing to migrate\" when the user tries to migrate a loaded wallet with no legacy data")