It takes time before cooking for food allergies, intolerances, or sensitivities feels natural. It requires time in researching where triggers can be hidden, time in the store reading labels, and then time to work through the process of altering recipes or finding new recipes. For those with guests coming in for holidays, the learning curve is steep.
If you take on the endeavor of cooking for someone with allergies or sensitivities, be sure to understand exactly what it is they must avoid. For example, apples could be fine, but it is the sulfites on the skin from the packaging while being shipped that poses the problem. Or perhaps lactose is the problem, but milk proteins are fine. Find out where the triggers can be found.
Ask for recipes or review recipes with them that you are considering to prepare for them. Go over ingredient lists of products that you are using in the recipe. Sometimes it is as simple as purchasing organic or using a particular brand, and the one living with this food avoidance will be able to advise.
Be cautious of cross contamination. We think of cross contamination when it comes to food-borne illness, but it is important to be mindful of this when cooking for food allergies as well. Keep the utensils, cookware, and the work area free of allergens when working with their food. Get an idea of how strict the avoidance should be. If it is celiac, even small traces of gluten could make them sick. Some people in the same room with someone eating peanuts could react.
When building the menu remember you can still have your traditional items without alterations and foods that are safe for your special guests. It might mean a few additional dishes to prepare. Discuss the dishes before the meal with the person avoiding certain foods or food components so they know which ones are safe for them. Working these details out ahead of time before the crowd arrives may be the most discreet and considerate way to provide a wonderful meal for them without drawing attention to the food avoidance.
Although, this is not a complete listing of everything to consider with cooking for those avoiding certain food items, perhaps it will help you in the planning process.