The previous thread  explained how to use the "find secondary parent" function. I didn't know that.  When I tried someone in my tree with secondary parents, it showed both sets as "Natural Parents"  I fixed it, but is this an error in the BK program to allow that to happen? I don't think you can have two sets of natural parents. Perhaps the program should flash some sort of warning if you try to enter both set as "Natural". Not sure what the alternatives are if you don't know their status - "Unknown Relationship" maybe.