Hi Emed I have to say this is a question I have as well! I am a recent turned mostly-vegetarian (ie avoiding what meat I can without inconveniencing others too much when I am visiting someone, etc). My 11 month old LOVES beans, tofu, lentils, etc but so far I haven't found a lot of recipes my 4 year old DD likes.
I realize I am the one responsible for her being hooked on meat as I gave it to her for 4 years, so I am trying to reduce our family's meat consumption gradually by offering a vegetarian/vegan dish at each meal with a meat side dish.
If my family likes the veg dish, great, I make a mental note that next time I don't need to cook meat with it. If they don't like it, I'm glad that Dd is eating something healthier than junk food (I know if she was still hungry after dinner she would beg for cookies, ice cream etc and it would really annoy me and I would probably end up offering her DH's lunch meat from the fridge instead--I choose meat over junk food for her)
I should mention that one other difference between our situations is that my DH is not 100% on board, altho he has been wonderfully open minded about trying the new foods. Because there is meat in our house anyway, it's hard for me to enforce a vegetarian diet on my kids or guests.
In only 2 weeks I have managed to reduce our family's meat consumption to 50% of what it was, and I hope to gradually cook smaller amounts and less often. I am starting to see this as a challenge for our family in addition to a personal challenge.
We have another challenge coming our way at Christmas as MIL will be here for 2 1/2 weeks. I plan to use the same strategy as with DD--if I suspect the veg dish will be "strange" for her I will offer 2 options--ie veggie burger and normal-- and if I see that she likes the new food I will offer it the next time without the meat. I do not want to starve a guest nor give them more fibre than they are used to so that it upsets their stomach. I am such a recent convert myself that I haven't even announced it to friends and don't feel comfortable enforcing my new diet on others yet. After I've been eating this way for maybe a year or so, I think I might feel comfortable telling friends and family "I don't cook/eat meat." As a more experienced vegetarian cook (finding out what meat eaters like, don't like etc) I might be more comfortable cooking a Christmas dinner with only veg food. At the moment I'm content with telling people that I've drastically reduced my meat and dairy consumption, but I don't label myself as vegetarian or vegan.
Because your DH is also making an effort however it might be nice for the 2 of you to plan your first vegetarian Christmas, finding out from your step daughters or their ...usual caretaker(s)...??? (sorry it was not clear who they live with) which of the above options would go over the best.
Thanks for letting me share my situation, I also have to say to the PPs I am pleased to see the list of child friendly food aboves and will defn give some of them a try!