Wordpress multisite

General information for the website: Community websites
Kind of development: Customization of existing website
Description of requirements/features: We want website setup so that it is a multisite solution. We have buddypress to manage the membership and wpmu membership plug in. What we want is each subsite to have its own members directory, but also we want an admin option to allow us to choose which sites can also display each other members as well.

So assuming I had site 1, site 2 and site 3.

I want an admin function that let's me , for instance tick a box to select which sites can interact, for example

Site 1 can also list members from site 2 and 3
Site 2 can list members from site 1
Site 3 can list members from site 2

With these settings activated a member of any site will see in the directory the members of their site and the selected site and can friend them and interact with them, the members avatar also is displayed as well.
Extra notes: