URI Restriction for Group Sub Nav

Hi,
i would like to know how i can restrict the members access to sub nav items inside a group. I managed to successfully prevent the group creation and link members to my membership otions page.

I was thinkning to restrict the access to the groups if the group creator does not pay his monthly mebership without restriction the access for others such as contributors to the group.

I find the file login-redirects.inc which defines the %% codes. Any idea how i can add the same for example %%group-name%%/admin in order to restrict this specific part or

restricting only the group owner the access if his membership expires?!

Thanks a lot and GREAT Plugin!
Ma

https://wordpress.org/plugins/s2member/