My twins will be 9 when we arrive, but turning 10 during our week there. Do we pay for half of our dining plan/tickets with kid's tickets and the other half with adult tickets?
Disney considers your child's age at the beginning of the trip to be their age for the entire trip. Basically, as long as you check in before their birthday, you will be fine to use child park tickets and child Dining plan for them the entire trip.