Another button on each page by the follower button that will say subscribe. This button would allow you to be notified in post notifications about their plane posts and forum posts. On top of this it can be configurable so you can choose what to be alerted of and where. So for example you can choose alert in jet stream or alert in post notification. Also another option can be check boxes of what to be alerted of. Like forum and plane posts.
If you like type +support in comments!!