New Strata Plan & Changes to Unit Entitlements

Seeking advice on the following issue: Is a new strata plan and revision of unit entitlements required when balconies are added to an existing strata scheme, or is there some provision where these changes may be unnecessary or can be avoided?

For example, can the owners simply agree or pass a special resolution to add balconies to some or all units without these changes, or is this unavoidable?

All advice gratefully received.