To answer your question: no, you cannot edit a module to be different from another instance of the same module.
You can, however, have nested modules. So if you would assemble your units based on that, you could have different modules, but underneath the elements are still a collection of modules. So if you edit the 'sub' module, so to speak, this would still change everywhere where this module is used.
In your example, make a module for the balcony. Include that module in the module for units with balcony, exclude it in units without balcony.
Erwin Edel, Project Lead, Leloup Architecten
www.leloup.nlArchiCAD 9-26NED FULL
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