I found 2 abandoned kittens yesterday. I have a female cat that stays on my front porch....however, she is not the mother of the kittens...she was never pregnant. This morning she has taken on the mother role for the babies including grooming and trying to nurse them. Is there any way for me to tell if the kittens are getting anything from her? Her nipples are not big...they look normal. I have been giving the kittens replacement milk...is this what I should continue to do?