When I am requesting an correction to a memorial - I normally have researched those changes and have found documentation to support those changes. Either through newspaper archives, diaries, death certificates, etc. I am not pulling these changes out of a hat.
I personally hate when looking at a memorial I don't know who that person is related to - to solve this issue I have made a personal goal to start with local cemeteries going through each memorial and tracking down their parents, children, etc. So lots of updated will be requested from others.
Please let me know if you need supporting documentation for the changes. I do attach many of the articles to the memorial when I remember to do so.