Thanks ya'll. I don't have a scale to weigh them. I could look in and see who was pooping when they were in the laundry room. But we had to move them to my bathroom since Penny learned to jump over the babygate. There is always lots of poop in their box but I haven't witnessed any from Resa, the one with the bigger belly. Tonight I put some kibble in a saucer of water and they drank it, I guess because it smelled/tasted like meat.
When they start eating kibble, do I stop the milk replacer and wet food?
The rescue's vet won't worm them until they're 6 weeks old.
Their wet food is 9 lives, all different flavors and their milk replacer is Hartz.