You can add 2 to 9 photos to a TUB Cards collection.
A TUB Cards collection is different than the TUB Sheet. You can add as many as 26 photos to a typical TUB Sheet.
But in a TUB Cards collection, you can add a maximum of 9 photos. However, you can add less than 9 photos, but you will not be able to play any game with the TUB Cards collection.