safely customize myth auth

i'm new using ci4,
i already customized the registration so it can send user's fullname,
i followed the docs https://github.com/lonnieezell/myth-auth...tending.md, but it is doesnt escape the value,
where can i put the escape before controller save data to database

and  i tried to add select role in registration, so when user register their account, it also add their account to auth_groups_users table,
i dont find the docs for it, so what i did is get the id from the user recently added to the table, and add this user to the group according to the role they were inputed, and i add this code in authController from myth auth, is it recommended way? if its possible i want to add those code in my own controller, but im new here.