In register form I have a radio field with three options: 0|Technician, 1|Shop, 2|Technician & Shop.
When first option is selected, i want to appear a dropdown with the categories of technicians and assign user to technicians user category.
When second option is selected, i want to appear a dropdown with the categories of shops, and assign user to shops user category.
Or, if third option selected, i want to appear both dropdown menus and assign user to both technicians and shops categories.