When I had looked in to this once, it seemed that one way to achieve this could be by adding logic to the feedback activity which determines which session the user attended automatically. Questions arose about how multiple attended sessions for a user might be handled, how multiple F2F activities in the course should be handled (which F2F activity to link to), and whether any attendance status should be used (probably not) or to only look for fully attended sessions to make the linkage.
In a basic scenario, there could be a configuration option to choose which F2F activity within the course that the feedback should link to. If there is only one F2F activity then it is obvious but perhaps explicitly setting that in the feedback is a good idea.
Options if the user fully attended multiple sessions
a)use most recently attended session
b)link it to all the sessions the user fully attended
c)require multiple feedbacks for each session (maybe not very feasible)
Just some ideas as I remember them from back when I looked in to this.
Jamie