What rides can you fit 3 people on? Some of our family is Pooh sized and some are toddlers. Possible to fit two Pooh sized adults and a toddler on any of the rides that hold 3?
We are bigger and rode with my nephew when he was 5 on things like nemo, Peter Pan, toy story (someone with no gun). Those are the only ones that come to mind. Dumbo and Aladdin work too no matter of size as you get two rows. Now that he was 8 it was impossible.
You have to be a bit proactive with pooh sized adults. Generally Disney is going to put as many in a seating as it can. Once you see the ride car you should be able to judge the situation and either all sit in row or request two. Don't stay silent if you question it though. It will lead to uncomfortable rides.