I would use the wildcard function. If I am looking for Maria Eriksdottir matches, I use the Find Person search, looking for "Mari* Eriksd*" That search will find all persons with the first name starting with "Mari", including Marie, Maria, Marietta, etc., with the last name beginning with "Eriksd". You still have to check around, but wildcard help.
But that brings me back to my question of three days ago: "Which name do you merge into: datter, dottir, etc.?