I find vegan and gluten-free tricky to cater for but not impossible. I'm GF and have not bothered to get a proper diagnosis because there's no point really, the outcome would be no different. I've no patience for those who are selectively GF, won't have bread and still drink normal beer etc. Personally I'd try and cater for this person and also provide decent non-GF bread for the others - GF bread isn't particularly wonderful. Vegan in itself is probably a very ethical response to life and something we could all move closer to and benefit both our own health and the health of the planet. So, yes, I'd try to cater for the new person and make sure what I provided was absolutely guaranteed vegan and GF plus I may get provide a few things that weren't like bread, butter and cheese for those who were not so bothered. I'd have a chat with her . For people who avoid certain foods, I always check if it's an allergy, an intolerance or a strong preference as well, just to be safe. No point having, for example, peanuts on the table if someone is severely allergic as the rest of the food can easily be contaminated. I won't die from eating gluten although I'd be quite unwell next day, I do know people who get anaphylaxis from the smallest trace of certain foods, eggs in this case, and for her, a vegan diet means she doesn't need to even mention her allergy.