I wouldn't mess around with trying to supplement any initially. Feed mom well and she can hopefully feed them all. Milk replaces can cause digestive upsets, so I wouldn't do it unless it's necessary. Weight the pups and keep track of their weights for or a week or two to watch how they are doing. My shepherd was able to raise 13 pups without assistance.
Hens go broody when you don’t want them to… and won’t go broody when you do. 