what shampoo is safe for 3week old kittens ?

yeah water doesnt get the poop smell out of them, never had this problem before cause usually i only take in one kitten at a time, but the lady who owned them, said the momma cat was found on the side of the yard dead, and they werent doing a good job of feeding them, one is a lot tinier then the other three, they told me that he wouldnt drink out of the bottle from them, but as soon as i got him and put the bottle in his mouth he drank happily, and the poop smell, when i make them pee, they poop as well, and god they really poop, but the poop smell manages to get into there fur and stay in there, so they need a bath really badly, i bath them in warm water last night, but it didnt get rid of the smell

well i went to the store bought a shampoo thats for cats and kittens, its suppose to be for there fur, so they wont get that many tangles, and dat many hair balls, it was the only shampoo, there was, the other one was a flea shampoo for cats and kittens, but my babies are bearly going to be 5weeks old, so there not ready for flea shampoo, one did get sick on me 3days to 4days ago and passed away, early this morning one of them started showing symptoms the same as the other kitten that died, but i put her on a heating pad, with her brother and sister, and within 2 hours she was doing better, she is now crying for me to feed her and everything, the biggest one is starting to get a bit of a attitude, doesnt like me to wipe her bottom to make her pee and poop, and she is very adventorous, always getting out of the box, and walking under my bed, as soon as i catch her, i put her back in the box, dont want her getting into anything, am feeding them every 3 to 4 hours,

tried giving them some wet kitten food mix in with there formula and a heat it up so it can be warm, but they dont want to have anything to do with it, so hopefully when there 5weeks old, ill try again, my kittens that have a momma, i offered them some of the wet kitten food mix in with formula and almost all of them took to it, started eating it, and there supposibly 3days younger then my orphaned kittens, from what the previous owners told me about the orphan kittens already spent 45dollars on them, and the previous owners want one of them back, so i have to part with one of them when they turn 7weeks old