How to make an JSON Mod Element similar to Recipe?

I want to create an Plugin that adds a new API Mod that allows for Data-driven Creations.

I thought that I could look into the Recipe Mod Element how to create it but I have some difficulty to understand what exactly happens.

Also I want to make it so that I want to create 2 JSON Mod Elements but one Mod Element if you add one for this Mod Element this will add it to a list of the other Mod Element.

For example if you create an Potion it will automatically add it to the List for the Potions. Something like that.