The only thing is maybe to check with the parents that they are only gluten free because often can be combined with other allergies/intolerance - you could do a beautiful gluten free spread only to discover also have issues with dairy etc. At DD party I know we have at least one child is gluten free but he is also dairy in tolerant and has issues with many fruits - I said to his mum about doing different cake but she said not to bother and would bring their own cupcake because finding food for him isn't easy and she would rather be sure ok for him. Her big issue is with lolly/party bags in that often parents recognize the issue with the spread of food but completely forget when comes to lolly bags - so he gets handed a bag of things he can't eat which she then has to extract from him.