Friends in one Ning are friends in any shared ning site. As far as I know you must request a friend and they can approve or deny your request. That would mean that you would have to do individual requests. I believe the founder of a Ning may have the ability to friend every new member.
"I think automation drives a huge part of the world we live in. Business and economic sectors provide automation to better provide faster experiences as engagement grows. By 2021, the education sector is sure to benefit from the features of…"