Granting an owner exclusive use of an area of common property and transferring title to an area of common property are two different things. Although they may have the same effect for most purposes, the legal requirements and consequences are different.
Granting exclusive use of part of the common property can be done by way of a by-law which requires approval by special resolution. You would want to make sure that the by-law set out in enough detail who was responsible for what in relation to that part of the common property. You would also want to look at requiring the person to pay the OC an amount of money for something which is in effect perpetual.
However, the property remains the property of the OC at law, i.e. the OC is the party on the title and that means certain things can’t be done with it, for example the person who has exclusive use couldn’t take out a mortgage using that part of the property as security.
If the OC wanted to sell and transfer the title of part of the common property there are a number of steps that would have to be taken, including a plan of subdivision that is lodged with the Titles Office, as outlined by Whale. And I think that does need unanimous resolution because effectively you are taking something away that the OC effectively holds on trust for each of the owners forever, so all the owners have to agree. You would think the Act would be clearer on that.