Mrs. Mahony: On the off chance you're still a member of this site:
Were you ever able to contact Don Dunham, son of David R Dunham of Florida, son of Dr. Roy Dunham of Canisteo, NY? I am Mary Dunham Szabo, the daughter of David R Dunham's younger brother Richard. I'd love to get in touch with Don if he is still with us. If you ever contacted Barbara Roggow (evidently the granddaughter of Katharine Dunham Bullock, David R. Dunham's sister and my aunt), who left a message on this board in 2012, I'd like to get in touch with her, too.
Don or his brothers (if any) or male descendants would be your only chance for a male Dunham descendant of Dr. Roy Dunham. His father David was married twice and I don't know about offspring from the first marriage. I never heard of Don until I saw his 13 year old message here (through googling his father's name). There was no contact between my father and his brother of which I was aware, although he and I both kept in touch with his sister Katharine until she died. Probably unrevealed (to me) closet skeletons.... No big deal; I have a few myself!
I basically have no information other than Jerry Crary's books (I have both, and the Richard Dunham/Laura Allen book is online, but if you're interested I can enlarge my portion of the family tree. My free subscription here runs out May 6, 2013.