If my child were vegetarian, I think I'd mention it in the RSVP. If you haven't sent out invitations yet, ask for any dietary requirements. If I were Jewish or Muslim I'd be upset about ham; if my child was lactose-intolerant I'd be upset about cheese - it's a minefield!
Could you do some ham and some cheese and put one of each in every box? Dairylea is always popular, marmite, jam, tuna mayo - other ideas that might suit. You can't please everyone, so don't try too hard!
Ok. Strange question. Are ham sandwiches in a party box an ok idea for 5 year olds? Just thinking if there are any vegetarians perhaps cheese is better. Actually, I am tempted to skip sandwiches as the kids never seem bothered. Any experience? Thanks!