@Sketch793Thanks to @PipMenace, when you set your guests as a group, it really helps to accomplish all your goals in a timely manner as your guests will all follow suit, which helps to ensure all goals are completed a lot more efficiently, as they will take the lead from the host of the event.
When I attempted the first dinner party, my sim did have a great reputation to start the experience off right. I made sure all her skills were high enough to host a good meal for the dinner, that she had a decent amount of charisma to open more choices for conversations, etc. but that was not enough... not without your guests cooperating.
For the first dinner party without the group setting, while some sims did come to dinner when called for the grand meal, the other sims were dancing or listening to the radio Other sims warmed their hands by the lit fireplace, or were busy conversing with each other while sitting on the couch or huddled in a group, and one sim actually drew a bath and soaked in my Sim's tub with a mud mask on her face! Plus my host sim sat and ate her meal at the kitchen table when some of the other guests sat at the dining room table. With the group setting, she sat at the dining table with her guests which made more sense.
When you are required to have at least a silver reward to complete these goals, having the group setting really allows your single sim to not only accomplish all them with one Sim alone if need be, you can also do so with less stress on you and your sim host. 🙂