We are at Disney this week. We had multiple reservations and when the rumored changes were first released, I was about to add the dining plan to our room only reservations anyway. I considered adding deluxe dining only to 1 reservation but since the plan was not made official I went ahead and added deluxe to both reservations. We really had no need to share but I was curious for future planning purposes so checked on policies at each restaurant. Our personal experiences:
Fultons - without us asking, server explicitly explained the kids could order from the Adult menu and we could share credits with others not on our plan
Mama melrose - kids could only order from kids menu. Use credits only for the number of adults/kids in the reservation
Garden grill - use credits only for the number of adults/kids on the reservation
T-Rex - use credits only for the number of adults/kids on the reservation. Kids could only order from kids menu for entrees, no appetizer entitlement for kids, kids could order adult dessert
Yachtsman - use credits only for number of adults/kids on the reservation. kids could order from adult menu (my 8 year old had a filet and ate most of it!)
Fultons - without us asking, server explicitly explained the kids could order from the Adult menu and we could share credits with others not on our plan
Mama melrose - kids could only order from kids menu. Use credits only for the number of adults/kids in the reservation
Garden grill - use credits only for the number of adults/kids on the reservation
T-Rex - use credits only for the number of adults/kids on the reservation. Kids could only order from kids menu for entrees, no appetizer entitlement for kids, kids could order adult dessert
Yachtsman - use credits only for number of adults/kids on the reservation. kids could order from adult menu (my 8 year old had a filet and ate most of it!)