I would ask Brother & SIL to bring a main that will suit their needs.
Then they can have veggies with everyone else, and you shouldn't have to prepare much extra!
I believe in manicures. I believe in overdressing. I believe in primping at leisure and wearing lipstick. I believe in pink. I believe that laughing is the best calorie burner. I believe in kissing, kissing a lot. I believe in being strong when everything seems to be going wrong. I believe that happy girls are the prettiest girls. I believe that tomorrow is another day and I believe in miracles.