Agreed, training more than one pup at a time is difficult and will take longer. I have 5 x 16week old GSD's with me at the moment and it is fun.
I would pick one word, doesnt matter which, because its the association with that word, not the sound that will work. Be consistant.
Ignoring attention seeking behaviour is a good one. Jumping up, niping fingers, you should put your hands under your armpits and turn just slightly so they get off, remain silent and dont pay them any attention. As soon as they display the correct behaviour then praise.
Question though, will these dogs be going back to the original owners, because if thats the case than Im afraid it will only start again. The best option is for them to go into a puppy class that targets this sought of behaviour. That way they learn and feel good about themselves as they teach the puppies how to behave.
PS you should add photo's they sound too cute.