"you must establish firm control over the electrician"
They must really want their shade installers to have a hard time. Fine, give me the wiring diagram then leave me alone. I have the diagram if I screw it up then that's my problem.
The minute they try to establish any control over anything electrical the home owner is going to make a choice of who's staying and who's going. I will not be told how to do my job by someone outside the trade.