Your Sims will automatically wear formal wear at wedding and pre wedding partys. For family gathering, there's also an alternate version available where they'll choose party wear. Bach parties remain untouched as they are already set to the appropriate party wear.
Ever since I first heard of the Sims 4 I knew I wanted a lot to do with the Grim Reaper. I mean ... obviously. And I was really intrigued when I heard about the hidden Reaping skill! What could it be for?