Ask your 17 year-old to make a list of what he would like in his lunch. Also, ask him to research some recipes for you. Whatever will be healthy for him will also be healthy for his younger siblings. A meat dish can be added for your husband and any others who want it.
Here is one dish we like as a main course. Layer peeled and sliced potatoes, carrots, onion, bell pepper, garlic in a large skillet. Add any of the following: broccoli, cauliflower, squash, cabbage, rutabaga, etc. that your family likes. Season with salt and pepper or whatever spices you desire. We usually add sliced beef sausage on top. Add 1/2 cup water, cover and steam for about 15 to 20 minutes. Don't overcook. Leftover roast or chicken would also be good to add for thos who want it. In a smaller skillet, you could make the amount your son would need and just leave off the meat. Drizzle a little olive oil over his... or not.
This layered meal is so easy to prepare and always tastes so good.
Another day, make a hearty vegetable soup. Add meat for those who want it. One pot does it all. Cooked beef or chicken can be added to the bowls as they are served.
Don't forget beets. They are good heated and buttered. Pickled beets in jars are good. Of course, fresh is always best and this vegetable is a good source of iron.
Loma Linda used to make canned soy products that could be used as a meat substitute to use in casseroles, chili, patties. Other companies make it, too, I am pretty sure. Seasonings make a difference on how good it tastes. I have seen a lot of new things advertised.
Here is a trick I learned last summer. You can steam cauliflower until nicely soft but not overcooked, mash it as smoothly as you would mashed potatoes, season as you would potatoes and serve. Most people will think it is mashed potatoes and they will instead be getting a good helping of a healthy cruciferous vegetable.
I am sure others will have many good suggestions. Check recipes, or adapt recipes from restaurants that specialize in vegetarian dishes. Be adventurous. Enjoy the wonderful family you have. Oh, and for something fun and easy, have a nacho night! Or loaded baked potatoes and a salad. Keep a bowl of fruit handy for snaking or dessert.