I have put about 20 hours into one character and I really don't want to restart.

I have all the requirements to marry Muiri (House, Amulet of Mara) except I did not kill the optional target in the brotherhood quest she gives you. Now all she says is "Thanks for taking care of my problem" Is there a gamefile I could modify or something that could trick the game into believing I killed the optional target because from what I understand that is the reason she won't marry me.