Momofcats, welcome to the forum.

It sounds to me that they are also reacting to being in a new invironment. If a cat smells the place of urination, even from another cat, they will often use the same spot for the same purpose. Like previously stated, you'll have to thoroughly clean up the premises, and then I would introduce your cats to the new quarters by shutting them up into a room with their stuff and especially with a clean litter box. This will give you time to clean up the remainder of your home.