I saw that thread... I dunno where you got your Step/True/Adopt info from, but some of them are dead wrong:
Amelie - Heart Problems - Not true. His aunt by marriage. At most, you could consider her sort of as an adoptive mom, but he never addresses her as such. There was an fan patch that converted her into a true mom, but that was abandoned at v4...and it's on v10.
Fiona - Reincarnotica - Not true. The body the MC takes over belongs to an orphaned child who was taken in by his friend's family. So again, unofficially adopted at most. There is no patch for this game at present, which is why it's not even on the HoI thread.
Debbie - Come Home - First of all her name is LISA, I have no idea where you got Debbie from? But second, she is nothing more than your dad's girlfriend. She's actually not even step, much less true... There is currently no public ipatch to change that. (It would require some minor plot tweaks, but it's definitely doable. So there's a chance once the game is fully completed, someone might eventually post one. *whistles innocently*...)
Mothers & Daughters - The dev has stated we are never getting any IC content with the MC's true mom in the base game... So I dunno about including her on an IC Mom thread? There is, however, an "unofficial" patch for the game which makes one of two other characters the MC's mom, and they will have actual lewd sex content with the MC. (Once the game finally gets around to that kind of stuff in another umm 5 to 10 years if I had to guess?)