What was my biggest Thanksgiving day disaster - and how could I have prevented it?

Well, you did ask, "How could I have prevented it"? Next time check the fridge one last time before serving the meal.

Always ask your guests to please let you know if they need or want anything. If something they want (i.e. a different salad dressing) isn't on the table maybe you have some in the fridge. That way they know that they can ask for something they do not see and not embarrass you or themselves.

I don't know about your family, but mine is out spoken. We say if we are missing something. Don't be petty, invite her to your family gatherings. She might not have known how your family is. Her family might be softer spoken. Give her another chance.

omg over cranberry sauce...just forget about it...u did a great job!!!

It must be terribly difficult being perfect as you are. I just bet the best blessing that sister-in-law ever got was when you quit inviting her over. You dear are the rudest person I ever heard of in my life. YOU forgot to put one of the standard must have foods on the table and decide it is her fault for not asking. you are totally so rude and inconsiderate I bet it was a pleasure not to have to suffer your company even if it only is once a year.