Re: Parhazee Khana anyone ?
People avoid certain foods for various reasons.
One of my friend's wife is a revert from Hinduism, and she is still a strict vegetarian. Muslims, especially desis, are notorious carnivores (as evidenced from your favorite dishes in the first post :) ). So anytime we invite her, we make sure there are a few vegetarian dishes or her.
When we invite older people (like, really old) we do ask them in advance about their dietary restrictions. Most of them can't eat spicy food, or oily food, so we do make separate arrangements for them.
If we invite a known diabetic, then we make sure there are fruits after dinner, in addition to or in place of usual dessert items.
If someone is sick and is on a diet of yakhni and khichri, then my advice will be that they should not be attending parties and dinners, and should instead be resting at home. Not to mention they may be contagious (sp?) as well.