Thats what families do and are supposed to do. They all are supposed to pull together when times get difficult. It shouldn't be just a one way street....and I can happily say that it isn't that way with my family. (Mostly...there are exceptions)
We've helped parents and they have helped us...(mine are more annoying and draining of resources and ungrateful but whatever)
However my grandparents once loaned me money for a truck...I paid them back with the same interest I'd pay a bank. I didn't care, I was going to
People need to wake up, you are getting 0% interest for keeping your money in the bank. Why not loan it to your family members for 2% interest? Suppose your son is paying 4.5% interest on their mortgage. Pay $50,000 towards their mortgage at 2%, they continue to pay off the mortgage as they were doing and the last $50,000 will go to you. Suppose that takes them 5 years before they begin to pay you off. They will save over $7,000 and because you helped their credit a lot you will probably help them in that way as well.
Now there is an issue with giving $50,000, you can only give $10,000 a year tax free. So what you do is in December you and your wife each give your son $10,000, do that again in January, and to top it off you give his wife $10,000 as well in January.
Meanwhile you make $5,000 in interest you wouldn't have made.