CBF – Your Owners Corporation (O/C) is aware that the Owner of the Lot made alterations to the glass sliding door, and I assume you’ve now confirmed that the door is Common Property.
That being the case your O/C doesn’t need a to put a By-Law in place to cover this and similar situations in the future, as one already exists as By-Law 5 in Schedule 1 of the Strata Schemes Management Act (in NSW) where Cl 1 states that:
An owner or occupier of a lot must not mark, paint, drive nails or screws or the like into, or otherwise damage or deface, any structure that forms part of the common property without the approval in writing of the owners corporation.
Additionally and again assuming that the sliding door is Common Property, your O/C is required to cover the costs of repairs, but it could as I suggested before Resolve to arrange and pay for those (to ensure that they’re done properly) and to then require the Lot Owner to make a contribution to those costs, which could be added as a separate line item to their next Levy Contributions Notice.
Frankly I’d take that approach even if the Owner’s contribution is a small amount perhaps equivalent to the insurance excess (even though your O/C can’t claim for malicious damage), because what will your O/C do on the next occasion that an Owner makes some alteration to a item of Common Property and damages or defaces that; will the O/C pay for those repairs also? I don’t see the point in an O/C creating a precedent now that has the potential to in future become a rod for its own back!
Finally and once again, I wonder what is this Owner going to do to permit access for her dog after the door’s repaired, leave it partially open on a permanent basis perhaps?