When Sasha was a kitten, I started feeding her "kitten food", and Tabitha (15 years older! ) her "adult cat food". But Sasha would finish hers and head to finish off whatever Tabitha had left. So, instead if trying to separate them, I just started giving them the same adult food. Both are doing well. Sasha is a well adjusted 2 year old and Tabitha is 17! Tabitha is a very petite kitty (always has been) and Sasha is about 12 pounds. I sometimes think that Sasha is a bit heavy, but then, I am comparing her to 8 pound Tabitha! (Tabitha has NEVER weighed more than 9 pounds, and the vet declares her in excellent health for a senior citizen )

So I guess my advice is if you don't want to separate them, Snoopy will be okay eating what her older fursibs are eating. I would suggest keeping an eye on her weight, though.

Of course, I am in no means an expert, as Tabby and Sashie are the only two cats that have allowed me "to live with them" and there are so many more folks on here that would have advice that is from more experiences. I am just letting you know what worked for me/us.!!!!!