Call Services on the Phone, an hour or so before the guests arrive. A Mixologist should be an option. You'll need a bar on the lot. I think it can be either the regular home bars or one of the 2 Late Night bars.
Once the mixologist arrives you can assign them to a specific bar (for example, if you have 2 or more) by clicking on the bar.
I've hired mixologists for several parties at my sim's home and at the University fraternity house. Guest sims usually ignore tended bars in my games and never get anything from the mixologist. I don't bother hiring them anymore.
You better have one of your sims family learn the mixology skill. The sim just makes some party drinks before the party starts and the guests will take and enjoy the drinks your sim made. Also if you leave the Late Night Professional bar its own, the guest will make regular drinks themselves.
Comments
Once the mixologist arrives you can assign them to a specific bar (for example, if you have 2 or more) by clicking on the bar.
I've hired mixologists for several parties at my sim's home and at the University fraternity house. Guest sims usually ignore tended bars in my games and never get anything from the mixologist. I don't bother hiring them anymore.