As an Admin I want the possibility to disable creation of new users from the "Raise on behalf" field

Problem Definition

At the moment, when agents use the JSM Customer Portal to raise new requests, they can use the "Raise this request on behalf of" field to create new customer accounts:

Some admins might not want to have this enabled.

Suggested Solution

It would be nice to have the option to disable the creation of new users in the "Raise on behalf" field.