adding a group content type button to specify the groupposts for that contenttype?

In the admin/og/og_content_types there is the ability to add a 'group'.
It would be great if you can add a group type as well.

As a siteadmin i want to be the only one to be able create the following groupstructure.

Groupcontenttype 1

Postable by groupadmin
Grouppost contenttype: article
Grouppost contenttype: message

Postable by groupmember
grouppost contenttype: message

Groupcontenttype 2

Postable by groupadmin
Grouppost contenttype: article
Grouppost contenttype: poll
Grouppost contenttype: message

Postable by groupmember
grouppost contenttype: message
grouppost contenttype: poll