Add more merged properties for PSBT2

Author: NicolasDorier

NBitcoin/BIP174/PSBTInput.cs

@@ -271,7 +271,7 @@ public void UpdateFromCoin(ICoin coin)
 		/// Import informations contained by <paramref name="other"/> into this instance.
 		/// </summary>
 		/// <param name="other"></param>
-		public void UpdateFrom(PSBTInput other)
+		public virtual void UpdateFrom(PSBTInput other)
 		{
 			if (other == null)
 				throw new ArgumentNullException(nameof(other));

NBitcoin/BIP174/PartiallySignedTransaction.cs

@@ -367,7 +367,7 @@ public PSBT Combine(PSBT other)
 		/// </summary>
 		/// <param name="other">Another PSBT to takes information from</param>
 		/// <returns>This instance</returns>
-		public PSBT UpdateFrom(PSBT other)
+		public virtual PSBT UpdateFrom(PSBT other)
 		{
 			if (other == null)
 			{

NBitcoin/BIP370/PSBT2.cs

@@ -191,6 +191,17 @@ public PSBT2Output AddOutput(Money value, Script scriptPubKey)
 		txOut.ScriptPubKey = scriptPubKey;
 		return new PSBT2Output(value, scriptPubKey, this, (uint)Inputs.Count);
 	}
+	public override PSBT UpdateFrom(PSBT other)
+	{
+		if (other is PSBT2 o)
+		{
+			if (o.FallbackLockTime is { } fallbackLockTime)
+				FallbackLockTime = fallbackLockTime;
+			if (o.ModifiableFlags is { } modifiableFlags)
+				ModifiableFlags = modifiableFlags;
+		}
+		return base.UpdateFrom(other);
+	}
 
 	protected override void WriteCore(JsonTextWriter jsonWriter)
 	{

NBitcoin/BIP370/PSBT2Input.cs

@@ -15,6 +15,20 @@ internal static void FillMap(Map m, TxIn input)
 		m.Add([PSBT2Constants.PSBT_IN_PREVIOUS_TXID], input.PrevOut.Hash.ToBytes());
 	}
 
+	public override void UpdateFrom(PSBTInput other)
+	{
+		if (other is PSBT2Input o)
+		{
+			if (o.Sequence != Sequence.Final)
+				Sequence = o.Sequence;
+			if (o.LockTime is { } lockTime)
+				LockTime = lockTime;
+			if (o.LockTimeHeight is { } lockTimeHeight)
+				LockTimeHeight = lockTimeHeight;
+		}
+		base.UpdateFrom(other);
+	}
+
 	DateTimeOffset? _LockTime;
 	public DateTimeOffset? LockTime
 	{