Balcony sliding doors pre 1974 strata plan

We are in a pre 1974 Strata Plan building. A number of unit owners have in the past changed their balcony sliding doors from a two pane system to by-fold doors.  and had them approved by the OC.  Now the SC wish to introduce a by-law to restrict people to only replace their balcony doors with a two pane system.  Can they legally pass a by-law that dictates what owners must do within their own boundaries as the doors are not Common Property due to the building being a pre 1974 Strata Plan?  I would appreciate any thoughts on the above.