Common – Can You Modify Common Property & What Are The Implications?

We are in the process of getting balconies built on our block – some of the OC want it to be common property – other want it to be added to the lot of each owner. Most want to “customise” the look of their balcony with different tiles.

The question is – can you customise common property in this way – or would it be better to make the balcony part of each owner’s allotment with the strata responsible for anything structural and the owners able to do what they like otherwise?