Gradually increase the amount of the substitute, until your family has become accustomed to the taste of the alternative. Don't give your child a great deal of juice to substitute for milk, as it may cause diarrhea. You might want to gradually add more water to the juice, until your family is accustomed to drinking it in a very diluted form. You might find acceptable waffles in a large supermarket or health food store. Look for a pancake mix or find a recipe that meets your needs.
Asian markets carry a variety of inexpensive noodles with acceptable texture and taste.
EnerG Foods has a brown rice pasta with good texture and flavor. There are various mail order businesses that cater to people on restricted diets. Buy one package at a time and experiment before investing in a bulk purchase. Once you have found products that your family enjoys you can investigate some time and money saving options. Your local market might be willing to order a whole case, which you can use, or split with friends on a similar diet.