If you can't get kitten milk use goats' milk mixed with the other ingredients. It is safe for kittens where cows' milk isn't (lactose content). I am not an expert on ferals, but I would try and get htem back with their mom if you can find her. Maybe put the kittens in a box that they can't get out of and she could get in when she hears/smells them. Watch and see if she comes back, and if not then take the kittens and feed them every two/three hours. But someone more expert may give you better advice.