Here is the official OFBiz line on this issue: it just hasn't been implemented yet.... ;)
So, you're right, the only way to get them in is through XML import, WebTools Entity Data Maintenance Pages, or some general database client tool.
-David
Nick Olson wrote:
> Is there a reason that the ProductStoreGroups are not editable in the
> Catalog Manager application? I needed to set up the groups so I could
> have different pricing rules on multiple stores, but I was only able to
> add the groups through the Entity Data Maintenance and XML Data Import
> tools.
>
> -Nick