Last name didn't change after getting married.
I moved two sims in together and when they got married, the female still has the same last name she did before they got married, and their child has her last name.
Forum Discussion
Hooray for EA listening to us! As of the patch released on the 26th, we can change our Sim's names just by choosing change appearance at the mirror or plan outfits at the dresser :)
Featured Places
