Implemented remove though will need to test more. Finished tweaking addItem(itemId, quantity).

FFXIVClassic Map Server/dataobjects/Item.cs

@@ -14,6 +14,8 @@ namespace FFXIVClassic_Map_Server.dataobjects
         public int quantity = 1;
         public ushort slot;
 
+        public int maxStack = 5;
+
         public bool isUntradeable = false;
         public byte quality = 1;