My b2evolution Version: 4.1.x

My b2evolution Version: 4.1.2

Perhaps you can help me with the following problem.

I would like to have the following configuration:

Blog A: public (read). The members of groups 1 and 2 should log in the blog A.

Normally, the two following blogs are invisible (blog B and blog C )
-Blog B: not public (no read and no write and the list with categories in the sidebar (widgets) is invisible) - only for Group 1.
-Blog C: not public (no read and no write and the list with categories in the sidebar (widgets) is invisible) - only for Group 2.

--> Something like "$login_required as Groupmember Group_1 = true;" in Blog_2.php ;-))

Hope I've described my problem clearly. I'm still a beginner with b2e.