The commands for gamestages work like this /gamestage add @p (gamestage) For example, /gamestage add Pvential ie
The names of the gamestages are ie for Immersive engineering, thermal for Thermal, tssn for tom's simple storage network, ssn for Simple storage network, ae2 for AE2, ars for Ars nouveau, create for create and ref for refined storage. you can give whatever stages you want to anyone, but i'd recommend giving 1 tech/magic mod and 1 storage mod per person.
The game stages limit whether you can craft recipes from that mod or not.