House training is house training IMO. Clean up any pee spots with an enzyme cleaner or a white vinegar/water 50-50 mix so he doesn't think so much about peeing inside.
My concerns would be
1) that they are very close in age and it can be very tough to raise two puppies or train to teenage dogs at the same time. Especially if the 6-7 month old male doesn't already have some decent training because he's probably getting large enough to be a hassle on a leash, jumping around, being a puppy butthead and be an issue at 30 or 35 lbs and growing. Rushing one out to potty, finding individual training time for each, constantly supervising both...etc etc
2) In pit bulls as in other breeds with a tendency towards dog aggression, it is often the case that they don't become dog aggressive until about 2 or 2.5 years; basically it can come on with maturity. I am in no way saying all pitties are DA or will become DA, just that having a puppy meeting another puppy and being friendly doesn't mean a whole lot for looking to the future. My opinion is that if someone is looking to adopt a pit type, either adopt one over the age of 2.5 years who has proven to be good with dogs OR be prepared for the possibility of a lifetime of crate and rotate. Note that I said possibility, because one simply has no way of knowing.
The big size difference between the two means that any slip or mistake should there be an aggression issue could be serious or deadly for the Chi. For example, I had a foster a few dogs back with some selective (leash/barrier) aggression. We were doing a meet and greet with her (~50 lbs) and a slightly larger (~60 lbs) pit bull. They walked fine together, sniffed fine together and then in about 2 seconds some dogs in another yard came barreling at the fence and my foster redirect her barrier aggression onto the other pit bull. In the maybe 5-6 seconds it took us to separate them, the larger pit had puncture wounds on her neck requiring vet care.
The flip side of all that is that I do know a number of pit bulls living happily with toy poodles, smaller "dingo dogs", other pit bulls, cats and even rabbits (under careful supervision). If you want the dog and are prepared for amount of effort to raise two pups and have the space or the ability to separate them in the future it needed, then go for it.