Am trying to find out if the following conditions could be achieved in "Customize Naming Formats" that meet our requirements. I've found how to pull the initials to start a username to meet our convention, but then I get stuck...

Our (all uppercase) usernames consist of:

First letter of first name | First letter of surname | 2 or 3 digit department code | 3 or 4 digits to separate the user (number of digits is whatever is required to take whole username to 8 digits total, as in 4 if it's a 2 digit department, 3 if it's a 2 digit department)

I understand the above will likely be too complex to do in one template, so I am more than happy to make one template per department so it doesn't need to work out how many digits to add, it will be set for anyone who we add as a new user in that department.

So for new user John Smith, a new staff member joining Department X which has a 2 digit designation of "55", I'd want it to create:

JS550001 (and if this is taken, JS550002, or next available one in the sequence).

So in my tests, I've got myself a template called "Department X New Start" I've so far got:  %givenName%1[U]%sn%1[U]"55" - how do I get it to add the numbers 0001 or next available?

Hope someone can help, thanks.