That is so sweet, respectful, and thoughtful to include you and their closest friends in the celebration.
I think you are on the right path to have some small bites. Make a list and maybe with some recipe pics and run it by DD 'B'. A tight group of friends at that age spend lots of social time together so follow her lead.
If i hosted similar at this time i would make a charcuterie sliced meats with the usual olives, gerkins, etc. And a cheese fruit similar. I make two of each indetical and keep the seconds covered in the fridge. A mix of various crackers separate as they get soggy.
The proseco tower is for a toast and i'm sure it has been tested with water a few times. Only ten so not difficult. One, three, six. A fine celebration and toast.
A sit-down dinner is so old fashioned and stiff. Small bits are easily prepped ahead and easily a meal.
I spend lots of time with this age group of young professionals at my work. So many are not about pig-outs on wings, ribs, hot dogs, nachos, burgers, tacos. (in moderation, lol) They will not starve if a light group of nibbles are offered.
We entertain alot, (pre-covid). We just make sure we offer and put out an abundance of food with back-ups in the fridge if needed. Always what we like so if we have leftovers it will not go to waste.
My personal go-to for this type of spread is a spiral ham with slider buns and mustards, horseradish cream....Ham warming in the oven, low and slow, and brought out after the initial celebration toasting with your proseco. I see no issue at all with a lasagna if you visualize a do-ahead the day before cooked 70%, then heated mid-early celebration. That age group does not make a big tray of homemade lasagna often so might be appreciated.
Nice thing about small bits is it is all diet/sensitivie/gluten-free/allergy inclusive.
My go-to this time of year are small skewers. Greek, italian, mini BLT's, Watermelon, feta, cucumber...veggie sushi, --California rolls, and smoked salmon rolls.
I make this salad checkered stack but with three high and skewered.
Q