I hope I understood your question correctly, it seems you want to be vegan but your family is against it? If so here is my reply:
Are you already a vegetarian, if not, I would recommend starting with that before moving on to a vegan diet. Vegan diets are no joke, and you can shock your body and easily become malnourished if you don't know what you're doing. Being a vegan entails removing any and all animal products from your life. Many vegans cut out the use leather, honey, dairy products, eggs, gelatin (marshmallows and jello have gelatin), meat, fish, crustaceans, fur, and I am probably missing others that aren't on my mind at the moment.
Please don't cast a spell on your family, for you are working against the will of others and it will likely be in vain anyways. Spells done on others without their want or consent will be blocked by their energy, especially if you don't know what you're doing and are inexperienced. Not to mention that this is generally frowned upon by most magical practitioners.
I would recommend studying a lot on the subject and sitting down to have a real discussion with your family. Let them know why you want to do this, and help them understand. Go to your local library and pick up books on the matter and share them with your family. Learn to cook vegetarian and vegan meals so you can be independent in that respect. Talk to your doctor or nutritionist to make sure you're going to be getting the proper nutrition. If anything, meditate and visualize yourself eating vegetarian and vegan meals happily with your family. Your best tools here are your personal will, communication, meditation, and knowledge. Although I'm not vegetarian or vegan (though I only eat organic animal products that have been sustainable raised and slaughtered) I highly respect that decision! Good luck in your endeavors!