Sometimes all you can do build the tree using traditional methods, note the contradicting information on documents/bmd and scrutinise the dna. I have one branch with some very creative birth certs and bmd entries that I revisit from time to time and although still not resolved I have chipped away at, several indications that one family group went to the USA look promising but it's accessing Fold 3 and newspapers that are holding me up though I'm not sure if descendants have taken dna tests. For now I'll settle for having the dodgy cert, baptism register and birth index entry on the profile of the problematic person in my tree. At best I'm looking at their grandchildren as potential matches but they would be someway beyond 3c to me.