Without source edit, it's gonna be really challenging, if not impossible.
onThrow / onMove will take most of the logic, and that's if your specific tfs 0.x has either of these functions.
Some do, some don't.
Your next issue is worrying about random shit, like trading with other players.
If your main backpack is full, it might throw that shit into your quiver type scenario's.
Same issue, but with quest chests or Npc's giving the player items via script.
I'm not certain.. but I don't remember a function that can find the parent container. That would be useful if it exists. might be something called a cylinder. Might not exist at all. Might have to create your own function.
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That being said, if you can figure out a way around all of...