I've been working on my family tree since 2007 and if it wasn't for Find A Grave I don't know where I would be. FAG has been such a tremendous help to me. Family lines I'm currently working on: Buck, Leroy, Rhea, Hollis, Gilbreth, Crawford, Robinson, and Owen.
I will be happy to transfer memorials that I have added to family members. I do not have to have "proof" that you are a family member. I believe that a family member can provide so much more info than the person taking the grave site photo and adding them to FAG.
There are people on FAG that don't like to transfer just because they are the ones who added the memorial. I don't believe this is a fair practice to the family members. There are also people who will email FAG superiors for no reason to get your items removed without just simply asking you to delete something or to edit something. It's very sad that people do those kind of things to other people.
The best thing you can do is just ignore them and do your best to honor your family members on FAG the best way you know how.