When my grandma passed away we found all their documents like marrige certificate, Granpa's discharge papers and my Great Aunt's birth certificate. I was going to put my granparent's marrige certificate in a shadow box with a bunch of pictures I found of them through the years, it turns out that my aunt had asked for it a while back and nobody had really remembered about it. Well anyways we are willing to give it to her but I want it back when she passes away.
Is it wrong if I type up an agreement between the two of us to sign stating that I just want my granparent's wedding picture and their marriage certificate? i'm just worried that my aunt's husband will make a huge deal about the fact that I want my aunt to sign this paper. It's really just because I don't want my cousins to turn around and say that their mother had promised it to them. There is already a lot of tension in my family and I don't want this to make it worse. But I just want this one item. She told my mom that she was already going to tell me that the marrige certificate would be mine, but like I said, I just worry my cousins would try to take it for themselves out of guilt of not visiting my grandmother in her final years.
Also what is the best possible way to word an agreement like that?