This pup will need lots of TLC. I think your other dogs are the least of your problems. Hopefully this puppy can lap up water/formula on his own- If he can it will make feeding him a little easier. I would definitely recommend you post in the breeders section.
I had to supplement my Roxy at that age because she was not tolerating weaning well. I gave her a goat milk based puppy formula.
For the other puppies- I also used it to soften the puppy kibble after I had ground the kibble into a powder to make a thick paste. Think slightly watery oatmeal.
Feeding Schedule for 4-Week Old Puppies | eHow
I would contact the breeder myself to see if they will let you have mama and pups. I would stress how unsafe the environment is if her child is shaking the puppies. If money is that tight than she really can't afford the dogs- IMO.