Yes I agree – this doesn’t just apply to balcony doors, it can be anything, for example a friend of mine is in a building where they did extensive works for a fire upgrade. The owners agreed that the rectification works that might be necessary for each apartment would be paid for by the respective owners.
If the owners insisted on the OC paying, they are paying for it anyway, and remember if the OC is paying they can determine who does the works. Save a lot of time and grief and get on with it.