How fun!! You're gonna have a great time with all this yorkie action.
I would get belly bands, you can order them from
www.barkindogclothes.com, i'd order a few if I was you and line them with a sanitary napkin/pad so you can change him all day like changing a babies diaper
and there are panties that you can buy at petsmart or petco , I think they're close to $20. You can put those on the female with a pad inside and change the pad as needed.
If I was you I'd order the belly bands online and buy some potty pads from the store and try to re-potty train them. Once they see how pleased you are when they potty in the right spot they might keep it up
Good luck and have fun!