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.
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Ok, it's not just me. I have to manage/merge my households too, and the last names don't change either. I knew the game would be stripped of a lot of features, but this should not have been one of them. I'm almost regretting not waiting for it to go on sale before buying it. At least there would've been an expansion pack and a patch or two by then.
