She looks fine but I am no vet.

I would try to modify your agreement to adopt Lily with your friends by saying that you will pay for a vet to test/examine Lily before you adopt her. This is standard practice for shelter animals to get the all clear before being offered for adoption (maybe breeders ? as well) and it is a perfectly reasonable request.

I agree you need to make sure she is healthy before you take her and I hope it all works out.