How to override item groups

How to override item groups?

The "override": true, that works for monster groups does nothing for item groups. "edit-mode": "override", does nothing too. New items are easily added but I want to also change the drop chances of existing items.

I spent about forty minutes trying to figure this out. I googled, I searched through the github. I tinkered with my json.

And I genuinely have no damn idea. If I’m honest, it’s pretty frustrating to have no friggin’ clue how to override an item group with a mod file. You can edit the main file, I guess, but it would get reverted as soon as you update.

=\ I would also love an answer to this question.

You need to update item group source code similar to what was done for monster groups in