I try to understand the possibility to create child categories if the user still can submit a ticket in the Parent category. The reason to have child categories is to have the possibility to apply the ticket to an specific child category or? It makes no sense if the user can still submit a ticket in the parent category. It is contra productive. Specially, if you have a complex support structure. If the user submit the ticket to the parent category, the manager of the specific child category will not be informed about the new ticket.
Could you change the code or where can we customize the code?