I found one with Marie N something 1873. According to Google, Minnie could be translation of Monique (Like Santa "Monica") Search could be done on any Leroy (Dornan) born in those cities and born 1872/1873.
(10 hours maximum including search in certificates) previous to the search of a couple named Leroy Dornan.
Marriage indicates residence of husband, so the girl could be born there.
(By that time, marriage always happended in spouse's residence and she "followed" her husband, so said Code Civil.
I understand no trace in Ellis Island (because opened after their arrival) so no date even approximative od departure?
Last option would be passport's request in Prefecture's archives. Could be done -and has to be done- in Lille through genhelp Club. ( am an active member of it, query may take a month to wait)