There's this helpful Vegetarian Diet Guide handout created by the Medicine and Nutrition Department at the Brazilian Vegetarian Society. It includes in depth information on benefits, nutrients, portions, pretty much anything they need to know.

I also found a bunch of articles on Google by searching for "guia de dieta vegana brasil" (vegan diet guide brazil). Some examples, specifically related to health and kids:

• Vegan Fitness - looks like a newish website about weightlifting and fitness geared towards the vegan diet

• Vegan Diet - quick article from a fitness magazine including a menu and some tips

• Vegan Survival Guide - Helpful article in a vegan blog, highly recommend reading the whole blog, but this article is a good start

• Vegetarian Guide - from the Vegetarian Center Organization website, a vegan-friendly guide that includes recipes, as well as all sorts of articles including newly vegetarian info and resources for raising kids in the vegetarian diet

I think these are good starters, but like I said, Google is their friend in this journey. Thankfully Brazil has been more and more vegan-friendly, so there are a ton of resources online.