I don't believe in trying 100% of the time to emulate the naturally skinny, but I do sometimes remind myself what one of them would do in such a situation if she had already eaten, since she didn't want to wait to eat so late or would rather eat with her hubby. She would likely put some food on a plate, eat a bite or two, and forget it. She would very likely not feel obligated to eat more than that for anyone else's approval. Or she might just skip the plate overall and have nothing solid.
Naturally thin people do not seem to fear other's disapproval of them for not eating. I think it's partly because it's usually so obvious that they are not doing it for diet reasons or to seem superior. They just aren't hungry! End of story.
If it's not the pressure of the group, then it's an inside job, and you need to remind yourself that you will likely feel better having a plan in place and sticking to it, no matter what. It's usually the randomness of our eating that does us in. Most people just aren't meant to eat randomly.
Alternately, and this is not orthodox No S, but I think can fit in the spirit of it, think of your dinner on this one day of the week as one in which you separate the foods into courses. The French can take hours to eat dinner. You say you're not sure what people will bring or whether you'll like the offerings but you also say that everyone brings delicious fare. You sound a little torn.

It might take you a few weeks to figure it out, but I bet you could have a small plate at home with your husband and have about a fist-sized serving of ONE thing that looks the best from the buffet. I'd opt for eating a soup or lovely big salad at home, possibly with some protein, since the party offerings are probably often good and starchy. Whether at home or away, savor every bite and then get on with the evening and the company!
But save dessert for the weekend.
Count plates, not calories. 11 years "during"
Age 71
BMI Jan/10-30.8
1/12-26.8 3/13-24.9 +/- 8-lb. 3 yrs
9/17 22.8 (flux) 3/18 22.2
2 yrs flux 6/20 22
12/20/24 24.1
There is no S better than (mod) Vanilla No S