this puppy can't go back there - probably they have got them out early becuase they can't cope. i agree it is very wrong - but they have the puppy now.
food e.g.
mashed fish/goats milk mix (fish from frozen blocks available at pets@home, or supermarket white fish is fine)
minced turkey/ goats milk yoghurt
really small amounts of course done very fine..., maybe 4-5 small meals a day - so not expensive - watch the puppy for reactions to the food they should be making solid but soft poos - diahorreah needs a vet visit.
and i think made up puppy forumla (human formula gives the squits) they can lap from a bowl if puppy is well and strong. (note: any illness in a puppy this age requires 24 hour nursing...if they get too weak to feed they are in real trouble...)
puppy is going to need alot of cuddling and play.
get a crate to be its 'home' and if your mate can, setup a little pen in whichever room they spend the most time with toys and vet bed lining- ideally puppy should not spend very long alone. they can be left for short periods to nap in their crate (puppies very much like babies in this respect!)
puppy should be put out to wee/poo after every little meal, and after every nap - they may still have accidents. set an alarm for overnight wee/poo outings - try at least every 4 hours (more often if not soon enough) and have crate by bed so you can hear when they want to go out,
The KC stipulates a minimum of 8 weeks.