Is it acceptable to feed an 18 month old Taco Bell and hot dogs?

[::mothernature::]

My parents adopted 3 girls, 1 is three and the other 2 are 18 months old. As a vegan myself I have a lot of concern for what my parents are feeding them, I find it disgusting... Is it acceptable? Would you feed and 18 month old a hot dog from a drive thru??