Hello,
In cases of inappropriate urination we always start with looking for a medical reason and start addressing the behavior possibilities. That means every animal urinating outside the box or inside in unwanted areas gets an exam and a urine check. It might be that one has a urinary issue and is soiling and the rest are following the same behavior because the area now smells like a place to pee. You have to clean so thoroughly they can’t smell residual urine (and remember their noses are so much better than ours!)
Also rhe stress of moving might be contributing. Or even the stress of the other dogs dementia might be a contributor. I use a lot of calming agent like feliway and DAP and add more litter boxes. Different kinds of litter and even try different kinds of litter. Try not to get angry at them. They think they are doing something completely appropriate and never do anything to make you upset or for spite. (Only humans do those things). If all of that fails you can try an oral behavior modification medication. They have worked well in many cases I have had.
This sounds like an obsessive behavior. I would be working on training and mental work daily in the hopes this can be curbed.
Hello,
I would also ask your vet about the possibility of focal seizures and whether a referral to a neurologist might be helpful.