Great job!!!! There is a paste, Nutrical, which has alot of vitamins and minerals a kitten needs. Get her some dry food as well. Canned food, while they love it, it has literally no nutritional value. Get dry kitten food. It has alot of good stuff in it to put some weight on her.

First rule of thumb is to get her to the vet and have her tested before you introduce her to your crew. You don't want to jeopardize your fur crew's health.

Bless you for taking this precious baby in. She's in good hands.