Hi Ami, im a little confused. I thought I read that Jill did not do well on Esbilac, but then read that she's on formula. What formula is she on and IS she still on formula? It is important that she continue with formula for as long as possible. We like to let them wean themselves. Some squirrels will continue to take formula from a dish after they refuse the syringe. Formula is the best way to prevent metabolic bone disease, which can be lethal.
When the time comes for release, at about 16+weeks, we recommend a soft release process. There is lots of information on this forum about how to release a squirrel to give it the best chance for survival.
Please read about the proper squirrel nutrition. I agree that items she may find in the wild are good to introduce, but that will not provide the proper nutrition while she's captive and growing. Momma would still provide milk.
I bet your granddaughter just loves a Jill. I have a granddaughter about the same age and she loved interacting with my baby squirrels.