First, let me apologize as I know that there are many threads on this subject already. But after reading them all, I am still confused. I have what I would have thought was a common and straightforward issue. The current plumbing is in the center of the wall and will need to be relocated about 15" to both the right and left. As usual the supply plumbing is easy, but the drain is confusing. Without opening the wall, is there a simple fitting that could be added to the current centered drain opening and then connected to the trap under each sink? Could you add a wye horizontally to the horizontal pipe coming out of the wall?