Formations are different from strategies. You cannot directly modify/add formations. TO see the existing ones go to Help window and go to formations tab. Changing formation, you should know that, if you've been playing around with fleets and their strategies
To answer your question, as i did in the other thread
yes, each fleet, unless it breaks formation, is like an individual ship - it is completely independent of anything else. If it breaks formation still the ships follow their own strategies, and the rest of the fleets are inaffected.