Well as we recall on our F2, you have to run the full roll through and rewind it to reset counter.
Done what your doing when we were testing the new P-30 ,, for development ect,. Would take a couple of shots and then cut, removed and reattached spool feeder that was wound on take up real, with tape. Closed camera and made a note, on what shot we were at,.on blank piece of paper that was inserted in the slot, that usually held the info on what film your were shooting,