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
Well, you could edit them in CAS by doing the cheat testingcheats true and then cas.fulleditmode and then shift-clicking on your sim to Modify in CAS, but people have been saying that it screws up relationships... so I guess we just have to wait for a patch? :\
