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
The cheat helped me a lot. Allowed me not only to change my sim's last name but also the relationships in the household. Although I am slightly disappointed there isn't an option for stepdaughter/stepmother/etc it allowed me to change the relationship from roommate to mother. Thanks a ton.
