Facebook – Tag a common friend and restrict someone – what happens

This is accomplished through the Facebook Graph API.

At Facebook's core is the social graph; people and the connections they have to everything they care about. The Graph API presents a simple, consistent view of the Facebook social graph, uniformly representing objects in the graph (e.g., people, photos, events, and pages) and the connections between them (e.g., friend relationships, shared content, and photo tags).

…

The connections supported for people and pages include:
Friends: https://graph.facebook.com/me/friends?access_token=...
Photo Tags: https://graph.facebook.com/me/photos?access_token=...
Photo Albums: https://graph.facebook.com/me/albums?access_token=...
Video Tags: https://graph.facebook.com/me/videos?access_token=...

…among others.

It appears there's no way to do this, unfortunately.

What I ended up doing was to do the going-forward arrangement, and then work back a couple of months, making corrections manually (#1). Better than nothing. There is also the issue of my comments on others' posts being visible. In my case, I think this is "good enough", though I do wish there was a better solution available (without programmering).

It might be possible to use the Facebook API to achieve this, but I didn't see anything ready-made with some quick searching.