Yes you would complain to the council and go through the proper proceedures you wouldnt hire your own builder to go on that house and start work with out their permision.
I understand that you feel you have a valid point however that point should have been voiced properly. How many voted to strke then went into work and are still part of the union? How would flight deck have felt during their dispute if they turned into work one day to be told the guy in the right seat is shadowing them so they can know what to do should there dispute carry on in to strike action.. oh and by the way can you train this guy for us please?