Lot owner is saying that because the engineer said their bedroom wall crack (internal wall) correlates to the one in the stairwell (common property), then that constitutes an overall common property repair, so even her internal wall gets classified as common property and she is not accountable for costs associated with installation of expansion joint, patching and painting for her internal wall. Does that sound right…?
An “internal” wall that adjoins another lot or common property IS common property. A majority of owners at a general meeting can demand three quotes (or however many you want). Get the signatures for an extraordinary general meeting (EGM) with that on the agenda. If you can’t get enough signatures (25 per cent of UEs) then you probably don’t have the support to get the additional quotes anyway.