Do you think it's a good idea?

Why not. I’m sure there’s an unending number of kids needing a real mom. And having had kids, grandkids, great grandkids around for 50+ years, you’re missing a huge amount of love and family without kids running up and digging that you are theirs. Even married with or without children it is still a even greater benefit to everyone to have another sibling.
I was once told by an 89 yr old friend the answer to staying young is to always hang with young people. He was only 94 when he died