Grant Rodiek, assistant producer of The Sims 3 Ambitions left this little piece of information in the following thread posted at the official Sims 3 forum:

Hi Chenmn123 — Sorry my last answer was confusing! We have some members of the Curious family in Twinbrook, our new town. Almost all the other families are brand new or created for Twinbrook by our amazing world team.

We did not add the Oldies, Crumplebottom, or some of the others you listed in this thread. We try to pick the families and stories we think best fit the latest game and town.

But, anything is possible for the future. We know that this is important for you and tons of other players, which means it’s important for us. I know this is cryptic, but I cannot say anything else.

I hope this helps!

Nice to see other families returning from the previous games!  Hopefully they’ll continue to do so for future expansions!  Props to SunhairSims for pointing this out via Twitter.