In my current save, he's now an elder and is the father-in-law of one of my played Sim's twin daughters.
I don't much play with premades but I have MCCC and I keep up with what they get up to. I also have a personalized save game I use for new saves. I've made some changes, like giving all the premades makeovers, changing things I don't like such as deleting Katrina (who the heck is she?? She's definitely not Nina and Dina's mother), changing Malcolm's evil trait to good, etc. So he started out this save living with Nina and Dina, but they both married other men and moved out. I left him in their home (ha!) and he eventually married and divorced Liberty Lee, my sim son-in-law's mother. River, the SIL, has a much better relationship with Don than with Liberty, even though Liberty is the one he lived with until he moved in with my sims. I found that amusing.