I have a demo ongoing in my house and need to replace the mixing valve for the shower. All the water lines are old galvanized pipes and I seriously doubt I can unscrew them from the original threads and attach new lines. What is the appropriate way to connect an old galvanized pipe to a new cpvc line? I know the whole house needs to have all the lines redone eventually and I plan to do that, but i need a fix to last the next year or so before I have that done. Thanks for any input even if it's bad news.