I would like this to have two options:
Default collaborators per form. So if I want my two backups to be automatically assigned as collaborators.
Allow the submitter to pick (additional) collaborators. This way if they need someone else in the loop, they will be notified.
Once collaborators are added, then it would be nice if when the form is submitted, that the collaborators also get notified in the INBOX as well as by email (if they are setup to receive those notifications).