This is so confounding! I know the "standard" is LNAB--last name at birth.That's great--if you can find a written birth record. Most of are forced to rely on records which were made when people didn't read and write "standardly." Census takers and law clerks spelled names the way they sounded from people with strong dialects who frequently could only make their mark when asked to sign a legal document. Sometimes, if there is a gravestone, I go by the last name chiseled there.I figure if they wanted a lasting stone monument for which they paid a stone engraver, the name there was most accurate. Women are harder than men, yes, because they almost 100% of the time before the last 50 years or so (in the United States) took the surname of their husband. But, if you can find a brother or some other male relative with records you might can glean the LNAB or correct surname from that. I wish you luck because this is a problem for all of us.