
well done to your friend for hand rearing them. It's hard work!
Sometimes substitute milk can make them a little constipated. If they strain & struggle to poo or if their poo is hard & dry ~ he could give them a drink of cool boiled water, this can sometimes help.
Tell him to continue stimulating them by gently wiping their genitals & bums with damp cotton wool.
They'll soon be ready to start solids, then I'm sure they'll be pooing loads!
As long as they are all healthy & happy & not bloated ~ they should be ok. :)