[ARCHIVED] Cannot edit pre-existing sims (Family relationships)

Product: The Sims 4
Platform:PC
Which language are you playing the game in? English
How often does the bug occur? Every time (100%)
What is your current game version number? 1.95.207.1030
What expansions, game packs, and stuff packs do you have installed? All
Steps: How can we find the bug ourselves? Depends on the pre existing sim
What happens when the bug occurs? A pre-existing Sim cannot have a parent or two parents at a time. When I go to edit said sim the option to have father/mother is absent. The play with genetics also removes the relationship.
What do you expect to see? I should be able to change a relationship to mother and father at will with cas.fulledit mode.
Have you installed any customization with the game, e.g. Custom Content or Mods? Never used.
Did this issue appear after a specific patch or change you made to your system? No

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This has been an issue I've had for years but with the new expansion focusing on family I decided to see if theres a fix. For the longest time I have tried to give a sim I created parents. I've managed to get a mother, but a father isn't possible unless I get rid of the mother relationship. It honestly makes no sense. I can't even create the parent in play with genetics because it removes the relationship instantly. It shows the father on the family tree as a blank profile, nothing should block the relationship. This has needed fixed and ive seen others complain about the same issue. I could technically add them to a new save and it works, but ive had this save since 2014 and my household is to large to keep every relationship if I did that. This shouldn't be an issue.