Need Advice on Potty Training Friend’s Dogs (6 month old puppies)

So, bottom line, I'm watching over my friend's two puppies for a month while he's on a field exercise. His two pups, Honey and Midnight (pit-lab mixes, roughly 6 months old), belong to the same litter as my pup Bandit (also around 6 months, pit-lab). Bandit is fully potty trained and has been since December of last year. Honey and Midnight are not. Won't go into a ton of details but their owner has not been having much luck potty training them, as he lives in an apartment with no yard and they are not fully vaccinated.

I'm looking for genuine advice, I'm overwhelmed with them and they have already created several huge messes in my house. Can't just give them back to my friend as I stated, he's gone for a month. Need any and all advice on basically potty training 6 month old dogs that are not mine. Any advice will help. I appreciate it in advance.