You problem will be resolved through the usage of User status and Network Header Validation.
What you need is to create one user status "CRTD" and in Validation prerequisite you can check that whether user status = CRTD and if its true then give your Network profile list <> to your list and give the message in message column.
Your problem get resolved that if you are trying to create a new project or network in CN21 with the not used profile then it will give you the error message and all existing project those are already released will not be hit by this.
Please find the Screen shot also for your reference.
You can modify also this validation as per your testing.
