Vegetarians at Thanksgiving I can manage, no problem.
Vegetarians at Passover is almost impossible. My husband calls it "the eleventh plague." I somehow manage when we have a vegetarian or vegan guest, but besides all the traditional and ritual foods that we aren't going to vary -- egg, gelfilte fish, chicken soup, and on and on -- it's really hard to make a vegetarian option, since I can't serve pasta, rice, bread, grains, soy, shellfish, yogurt, anything with cheese or dairy, etc., etc., etc. I've seen vegetarian seder menus, but all the other guests definitely want the traditional menu, which is so complicated to begin with, it's the last time I'd want to make a whole separate menu for one guest.
Count your blessings!