I hope it is not too late, but have youtried Karyo surup? babies need sugar and it is a thick and concentrated. I went trough this with a couple of kittens. We almost lost them. They were shaken severely by a child. They couldn't eat, so we had to rub the syrup on their gums hourly. I had a mama and a kitten dumped off at my shop door this morning. Cute little ragdollish cay and a calico kitten @ 4weeks. I walked up to the door and they were in a carrier...People just never surprise me anymore.
Good luck with your little angels. How blessed they were to have found their way to you!!