I think the fact that she is sleeping in bed with them is a great sign. We had a very shy foster, and her first sign of being lovey-dovey was sleeping with my daughter. Although I love my cats, it is the kids who made them what they are by spending hours loving on them. Although it takes care to keep a pet safe from a baby, overall children are a huge plus to any pet, IMHO.
I am glad they are giving her time. I hope it works out for all concerned.