It is separated by room though. You said there are 8 people for 8 nights correct? Just for example, lets say you have 3 adults and 1 kid in room A, and 1 adult and 3 kids in room B.
Room A will have 32 snack credits, 32 CS credits, and 32 TS(24 adults, and 8 kids.
Room B will have 32 snack credits, 32 CS credits, and 32 TS(8 adults, and 24 kids.
Each of the 4 people in each room will have access to all the credits for their room. So, if you all stay together all the time, when it comes time to pay for TS or CS, you'll just need 1 card from each room.