Right now all JSON files are in a hardcoded set, and if you want to add new files you have to add them to the C++.
What I’m suggesting is an additional data/mod/{modname}/ directory that contains JSON files which will be merged with the “main” ones.
For instance, I could have an “extra_food” mod, which I’d put in data/mod/extra_food, and then I would define my new food items in “data/mod/extra_food/raw/items/comestibles.json” and my new recipes in “data/mod/extra_food/raw/recipes.json”.