I agree with JimmyT that there’s probably no legal basis to insist that all communications to the SM go though the chair.
It can for sure be requested to be done that way and might make sense for most matters but I doubt it could be upheld or that a lot owner could be charged for not doing it.
There have been some published VCAT cases of “troublesome” lot owners and they were dealt in other ways. Eg the SM stopped answering their calls and simply forwarded their emails to the committee.