I've booked YN seats for myself and three family members for a DEN-HNL flight later this year. I don't have any United credit cards.

I can't use GPUs or RPUs to upgrade, correct? The kids are small and we have the two rows of two seats, and I don't consider this that long of a flight, so I'd rather not burn instruments anyways.

Am I eligible for a CPU? They wouldn't be dragged along with a CPU, correct? If I am CPU-able and they are not, how do I make sure that I just don't upgraded- or better yet convince my wife that there was nothing I could do and I'll see her in HNL?