Thanks for sharing all the cool stories.
All partners of my game-born simmies have had a previous birth... But they'll never know.
I always pre-plan the kids future... to the extend that they are going to school with their future husband / wife (with 3 flashes!).
When I started that, I made a lot for one of the boring standard sims, used the summoner (from the insimenator) to summon the kid(s) of my favorite family. I had them choose the age of adult with the insimenator, used the hacked crystal ball to find the teen/YA/adult who matches their aspiration most (I set their likes and dislikes to totally improbable combinations, like 1. zombie 2. plant-sim and the dislike to athletic).
I have them flirt a bit and scope the room for better matches (I get several possible matches with the hacked crystal ball, don't remember who did it on MTS2). When I find a suitable match, I exit to the neighborhood without saving, then go back to that "lab" place and teleport the ppl in who they had the perfect match with... Next I make them quit their jobs and delete all their memories (carrigons hack). Then I shrink them to toddler and let them grow up them to child... (all with the insimenator).
Then... I go and play the "family" lot, after saving the "lab" one. I summon the kid(s) with the summoner, move them in (with the teleport picture or insimenator).
Now, as soon as they grow to teens they will want to fall in love with each other and are bonded for life.:tongue8:
Sound a bit like frankenstein, isn't it? But it works perfectly for me

Poor simmies will never know that they had a previous life...