Tanya, how about turning it around and and YOU feeling offended that there is no suitable food for you.
Of course you can make a plate up and take it with you, I do it so often it's expected of me now, it's just something the family will have to get used to.
I once went to a Christmas dinner at my sisters and only selected the foods I could see looked healthy.
The turkey looked safe WRONG, it had been bathed in sweet, salty juices whilst cooking. I also ate a little ham and it made me gain weight too. The salads all had dressings, so I only took a tiny amount of them.
Then the desserts came out, there were fruit mince pies, cheesecake, christmas pudding with whipped cream, a gingercake with icecream, and a Pavlova.
I ate non of these and I felt starving yet I still managed to gain weight
I believe that the only way to assure that your meal will be healthy is to prepare a plate of your own to eat.
The idea I think is just to enjoy eating with your loved ones, it's not about who has prepared your meal.
Perhaps you could even make your plate up to be healthy version of what they are eating, that way no one will hardly notice