Is there an alternative to "extend" for item and recipe groups?

I want to be able to add entries to item and recipe groups without having to otherwise overwrite said groups in the process, but apparently “extend” isn’t the right option. Does anyone know what the right option is?

EDIT: When I said ““extend” isn’t the right option,” I meant because it apparently doesn’t work for item/recipe groups. Sorry for not making that clear.

Extend doesn’t overwrite, it extends. That is what extend is for.

I know, but it doesn’t work for item/recipe groups, so I need to find an alternative that does the same thing for those that extend does for everything else. Sorry for not making that clear in the first post. I’ve been kinda sleep-deprived lately…

Extend does work for item groups? Cataclysm-DDA/doc/ at e2849413652046d350909ab9cfc3780d304bbf77 · CleverRaven/Cataclysm-DDA · GitHub

Though I don’t know what a “recipe group” would be (nested category?)

Last time I checked, it doesn’t work, and I’m not the only one to have noticed this.

As for recipe groups, I tried using it as it as a way of adding to crafting recipes at basecamps as recently as this morning, but it doesn’t do anything in-game, even as it otherwise runs without giving any error messages.

If extend doesn’t work for item groups please open an issue with your examples, that’s explicitly supported and we’ll have to wrangle it back into shape.

I don’t have those examples any more, unfortunately. Should I do that for the recipe groups, though?