I have 18 DNA matches that Thrulines connect to my 3G Grandfather Thomas Donald, 12 of which I have confirmed myself.
5 are through his two sons by his first wife Martha Steel (my 3G Grandmother) whilst the other 13 (12 confirmed) are through his second wife Janet Brown.
I had already seen Thomas appearing in other trees married to Janet Brown, but prior to the DNA evidence I had no "proof" that the Thomas Donald married to Janet Brown was indeed the widower of Martha Steel.
So my answer would be that DNA can provide evidence alongside the usual paper trails to confirm a match
