Cannot set parents for pre-existing sims

I've got a new issue, in regard to relationships.  Louise, my Sim, was pregnant with her last child. Her eldest four are teenagers.  This is my fourth go-around trying to get my main family to where they ought to be. They are still married, thankfully, no longer listed as cousins, since they finally moved to Bellacorde.  However, I did check using MCCC on Louise's pregnancy before the move. Joseph is listed as the partner used to father the child.  This showed all the way up to the moment of birth. Yeah, I used MCCC during her labor. Joseph is the father. However, after the baby boy was born, just out of curiosity, I checked the family tree. Que the music dah, dah, dah . . . 

Little newborn Adrian is listed as Louise's Secret Baby.  If this isn't a bug, but rather a nice juicy bit of intrigue sewn into the game, I'm okay with it. This could make for some very interesting gameplay. Until I end up pulling my hair out by the roots and holler, "Too much drama!"