I'm sorry that you are worried that your nephews will be abandoning you now. But they may just be busy with the holidays, or just need some time before they make contact again. All may not be lost
They sell sticky strips to put on furniture, etc that cats don't like the feel of and they stop scratching because it's no longer enjoyable. I will see if I can find the name of them.
Felaway does have an expiration date. I ordered some of the spray for myself yesterday to try to see if they will stop scratching, and will let you know how it works out. I told my husband I bought it. He seemed happy. I think he wants a new couch, too.