Ultimate Party is a free mod for the game, which allows you to customize parties, add rowdy and relaxed sections, and more. It's made to be compatible with all the different DLC packs for the game, so it works with all of them. This is made possible by using a new system called phases. When you play with the mod, you will be able to change the phase at any time, so it's possible to go from a relaxed phase to a rowdy phase.

If you want to use the Ultimate Party, you need to first download it, which you can do from the link provided below. After the download is finished, open the application, and click the button that says "Run".