Another Vet Question - Puppy Weaning?

Hello all. We have Xolo puppies that are 4 weeks and 3 days old. We’ve been trying to get them to lap up milk replacer from a shallow dish almost every day for the past week. I know they can do it, because they have lapped up the milk at least once, but they don’t seem to want it. The mother does not like to nurse them, and she will only do it for a few minutes every day. Sometimes she growls at them when they try to nurse. Should we start trying to give the puppies food (blended to make it like mush obviously)? Should I be forcing the mother (holding her down while they nurse) to feed them?