How do I add an existing subdirectory blog to primary site admin list of sites?

I have 3 sites and somehow I split them up. I’m admin for all 3 but they are split into 2 groups. Network Admin lists all 3 sites but Primary site Admin only lists 2 sites.
I would like my Primary site (blogs mu theme) Admin to have all 3 sites listed. 3rd blog BuddyPress activity is listed on primary site but not the 3rd blog.
What can I do, please help.