Fold the baby down on its knees, front and back. Rather than push baby to the teat bring the teat to the baby. Open its mouth and put the nipple in it. Squeeze some milk into its mouth. It will figure it out. Don't waste the colostrum. Freeze it. Or put it into a syringe and slowly syringe it into the slow baby's mouth. You need to get food into the baby NOW! Don't wait for it to get it figured out. They don't have a lot of reserve to keep going. I sometimes put a nipple on a 60cc syringe and feed that way. I've had good luck with the folding thing. My nigi's are close to the ground and the baby's can be taller than the teats.