Of course it’s safe, it’s probably the safest way to raise your children because it doesn’t expose them to antibiotic resistant bacteria, zoonotic diseases, the horrors of realizing you’re needlessly contributing to animal suffering and ingestion of their body parts, organs and secretions, and a well planned vegan diet is not just “healthy and appropriate for every stage of life” it’s also most protective at decreasing one’s risk for chronic disease and all cause mortality. Also, there’s endless longtime, lifelong, and even multigenerational vegans out there doing incredibly well and significantly better than the average person. If anything, raising your child vegan is the safest way to raise them.