I have a use case where we have about 100 named users added via Active Directory and 300 participants which are added to Forms as needed manually.

If I create a form process in which I would want all Forms users to be submitters, is there a way to create a team within Forms to encompass all users?  

Basically, I would like a low-maintenance solution.  Even if it involves just the named users being added as a group, the participants can be added as needed.