Hey Cami.
At under 13 weeks, Romilly should really still be at home with her Mummy! She will only just have started being weaned properly, so her diet is going to be tricky to settle. DON'T PANIC though - There are lots of options on the market, depending where you live.
You need to get her kitten food, and ensure she is is getting all the nutrients she will need to ensure strong bones and system for adulthood. Speak to your vet (she will need a check up ASAP) and see if they have any over the counter recommendations. There are so many Hills varieties under the Science Plan banner, you will need the specific type if you want to try getting her onto that. She is too young to be on raw food at the moment, so if she will eat the chicken, then make sure it is poached, and add some of the cooking juice to her bowl to help ensure water intake! It's a sneaky insurance policy - especially if you want to feed her on mainly dry when she's a bit older!
It was a bit soon really to introduce her to Liara, as they could cross-contaminate if either had any bugs from their breeder, but that is done, now, so put that aside. Try to feed Romilly little and often, away from Liara, that way you can ensure she gets what she needs, and help stop Liara from pigging out too much!
You have her now, and the introduction sounds like it worked. Enjoy watching them grow, and remember to give both lots of luvs and cuddles!
BY THE WAY - PICTURES ARE NOW REQUIRED!