Suggest to them that they can do it anonymously.  Instead of using their name, they can make up a name or use initials and you could be the manager of their DNA.  Nobody could possibly know who they are.

Robert Hanna
NYC

Researching Chanan, Hanan, Hanna, Hanne, Heine, Hiney (Warsaw); Blumenblat (Poland); Karasik, Thomashow, Cohen (Babruysk); Rubinstein, Bunderoff, Pastilnik, Nemoyten, Diskin (Minsk).