Just have some honest open communication with the guys coming to install them. Ask them why they are doing what they are doing and if you dont like the answer, tell them you don't want it done. It is a tough spot for sure, but you can demonstrate how your stairs move with those shims under them. Say that is not ok. If they try and shim up the whole front, the middles will move and that is still not ok.
I mean, if it were me i would laugh at them and throw them out of my house but that is because I know better and have no skin in the game...and because I am an asshole.
I wish you luck though.
I mean, if it were me i would laugh at them and throw them out of my house but that is because I know better and have no skin in the game...and because I am an asshole.
I wish you luck though.