Social Networking

I’m looking for a social network with advanced control over privacy of postings and comments. For example: I’d like a user to be able to specify one or more circles for a single post (say Circles 1 and 2), and when someone from Circle 1 comments on that post, only people from Circle 1 can see that comment, but not people from Circle 2, and vice versa. I’ve done some digging, and I can’t see such capabilities offered out of the box neither by the major social networks, nor by the social network platforms.

The existing networks I've seen allow you to specify only one circle for each posting. And each posting comment is visible to all the people targeted in the post. It seems like I need to create my own social network using a platform that would allow me to custom-code against its APIs to modify its posting and commenting behavior. I’ve looked at a few platforms available, such as DolphinPro, OSSN, PeepSo, Ning, HumHub etc but I can't see if it's doable or not. Does anyone know what would be the most straightforward way to accomplish that, and which platform would be the easiest to deal with for such a requirement?