Jersey Week is not terrible at all, I was there last year during that exact time. I definitely used other websites to plan which park on which day and it really helped. You could switch your reservation, but to me it sounds like your ADRs are a pretty high priority to you. If you were to switch, while an ADR may open up for the restaurant you want, it may not be at an ideal time. Switching is a gamble, but the temptation of the POLY is strong. If it were me I would keep everything as is. I'd plan to go to the POLY when the room is bigger and all 3 kids can enjoy the volcano pool, Aloha Dinner Show, etc.