Creating a web group through Web Services

Question

User web services, we're able to create Presentation users merely by calling SAWSessionService's logon or logonex methods. But how can I create a web group?

Answer 1

Yes, I'm using 10.1.3.2. Let me give more detail.
Our RPD is setup to perform external database authentication. We use initialization blocks to perform this, and it works great. We can "login" by using NQUser in the URL or using the login or loginex methods. If the user doesn't exist in the presentation catalog, the user gets added if the authentication is successful.
We've been using web services to create catalog objects (dashboards, folders, etc.) and add ACL to them. But we've been doing this on a user-by-user basis. Now, we wish to add ACL for groups instead of users. But step one is to first create a presentation group. We can't find a programmatic way to do this. At first, I assumed we could create a catalog item via WebCatalogService's writeObject service. But when looking for the XML that defines a "group", we found out that a group is not defined by an XML. As someone wrote previously, I can't find any other service that creates a group.
Once again, can a group be created through OBI's web services? It feels like it does everything else.