For old Norwegians, I often find that there are two spellings for the daughter of "Erling" or some other such name. I know that Erlingsson is incorrect for a daughter, but has a decision been made as to whether to merge to datter or dottir? Dottir is probably correct for the time period, but datter is the commonly used name, and many times there isn't a "dottir" to merge into.
For consistency, I think this is a program/policy decision that should be made and followed, but I'm not the one to make that call.