IM also lactose intolerant but kids tend to get it worst
I would buy a cookbook on lactose intolerant for kids

its so hard to prepare food without having an allergy to contend with.
soymilk or lactose milk
dairy free ice cream products
soy cheese
there are alot of lactose free products

im lucky my biggest issue is dairy like icecream but milk in products is ok; but the red dye u mention is in alot of processed foods-stick with fruits/veggies/meats/grains-should be ok; i would offer this for everyone in the family but u can still make a milk based meal for your other family members.
the fruit aisle has really yummy juice all natural thats veggies/fruit combo