I don't have a solution for this but I do believe there is such a thing as revenge peeing. My 7 year old Dachsie started peeing on the floor shortly after we took in our little Yorkie almost 4 years ago. When she passed last month, he did not stop. Now that we adopted our 5 month old YorkiePoo and we are working on potty training him, the Dachsie basically does not get much chance to be the one that pees on the floor (except today that is). We feel he is jealous about losing some of the attention but he still gets a lot.
I wish you all the best in trying to correct this issue. They certainly have minds of their own and they know that they are the real bosses.