wlou - Given that you're selling the house, you might consider offering the buyer a credit for the estimated amount of the repairs and let them do with the money what they will. That way if the piping gets replaced, it the buyer choosing who do have to it, etc. If necessary, maybe just bump the credit amount up a bit to sweeten the deal for them........and to get it off of your plate. That way if something goes haywire during the replacement process, it's in their hands and not your issue to deal with.
Just a thought.......
Bill