We have vegans, vegitarians, lactose-free, peanut allergies, no red meat and celiac persons in my family so I hear you on the balance between feeding everyone and still having it be doable for you!
I'm lactose intolerent so try and avoid dairy, so my question to you would be is it an allergy (go into cardiac arrest if they touch dairy) or an intolerence. And for both is it the lactose (which is found in the dairy fat) or dairy in general if theres allergies...Ask them because this makes a huge difference...there is lactose free cheese that can be used as regular cheese and I would recommend using that and making the same thing for everyone if they are able to eat it....I hate having to eat something different then everyone else if it can be avoided. Also maybe try and look up vegan or vegitarian pasta options as everyone would be able to eat those.
If they can't have lactose free products, I would suggest a pasta bar with a couple different sauces because people have such unique food needs (does everyone eat red meat? If not then the mtballs don't really help those people...etc)...maybe a pesto sauce, a white sauce, a tomato sauce with meatballs on the side that can be added if people want them and/or a meat sauce and then just one or 2 kinds of pasta with a green salad or ceaser salad?