Usually I would give the wood spawner an instance variable, a kind of ID, so the first one var is 1, second one, var is 2 etc which you can pull from the wood spawner's own IID (instant of that object type). Then any wood spawned from it, you can set an instance variable on the wood to match the spawner. So something like spawner - spawn the wood. Wood set wood.variable=spawner.variable. Then any wood marked as 1 has come from spawner 1, marked as 2 from spawner 2 etc.