DNA matches tip
 

An idea I had today. If you have a DNA match on ancestry who has a private tree, and there are "shared matches" whose trees you can view, try searching your match list for each surname from those other trees and see if the person with the private tree comes up for any of them. Since the surname search does kindly let you know if you have guessed a surname in a private tree! This might give you some clues as to how the group of shared matches are connected to each other and to you. It worked for me.

(I'm assuming you have already searched your match list for the surnames from your own tree.)

Does that work if the private tree is set to not be indexed?

I wouldn't have thought so, but can't say for sure, Nicki.

My private tree is set to be indexed but without any "Ancestry" sources on it (I'm not re-doing everything on it that I have offline) I wonder whether it will get indexed as, although there has been a debate about that on here, from what I've heard Ancestry won't index any person on a tree without any of their own sources attached to the individual. Will have to wait and see, am somewhat uninclined to make it public.