Different eaters

Feed your 6 year old the same you will be eating, and let the vegetarian fend for themselves .

I was a vegetarian for many years and my parents used to cook the meat separately from the veggies / carbs. I would eat the side dish + vegetarian version of whatever. So no crock pots or casseroles.

The six year old needs to learn to eat the meals that are prepared. Growing up, we didn't have a choice. We sat down to dinner, whatever my mom had prepared. Its not a punishment, it just helps develop good eating habits. You can do many vegetarian meal ideas that will appeal to most. I make pasta with vegetable-based sauces(you can even blend some veggies into spaghetti sauce) and serve with mushrooms and cheese. You can always make a meat on the side to add to a plant-based meal. Beans, lentils, quinoa, and peas also have protein. Try Allrecipes.com they have lost of vegetarian recipes.

You might try cooking a batch of ground beef or turkey or chicken and a batch of lentils each week. Then for dinner reheat some beef for you and 6 yr old and some lentils for vegetarian. It can be seasoned so many ways. Taco, marinara, sloppy joes, bbq, etc. It can probably be done in the microwave. Then the rest of the meal can be the same rice bowls, stuffed potatoes, pasta, sandwiches, tacos, burritos, quesadillas, pizzas, etc. Get your vegetarian to help. Good luck!

Build your own salad! Chop lettuce into bite size pieces, separately stack diced tomatoes, olives, mushrooms, cucumbers, whatever veggie options you have on hand. For protein, hard boil a couple eggs, dice some ham, shred or cube cheese, and have some kidney beans and nuts or seeds on hand. See what salad dressings are in your fridge and let the kids go through and fill their plates buffet style

Mostly because I grew up in the south and hated collard greens, shrimp, crab (most seafood) and most of what my mom/grandma made and I was forced to eat it. As a result I instituted a one bite rule. No matter what I made the kids had to eat one bite even if I just made it the night before.

When my son went vegan (in his teens) I accommodated him, sorta.

I prepared whatever I was making for the rest of us but I would make a side that was vegan. After a few months of "how is he going to get enough protein" I started the whole family having one or two vegan nights, there was very little pushback from the rest of the family.

Different diets for different family members doesn't mean you need to become a short order cook. Just means you have to get creative with main & side dishes:).