We will probably need some additional API support to make this possible. We need the ability to filter down to a specific site+path so we can generate the activity panel for each document. Also we may need to introduce additional feed event types, for example an event when somebody makes a comment, so that we can see those comments in the event feed when we are filtering down to either the target document or the author account. (This gets even more tricky when the signer does not match the author)