Unlike like WC3, everything is based on universal base data. This universal base data in the case of some data types (behaviour for example) is derived by extending an utmost base class with additional fields.
For your maps I advise duplicating all your data and shifting their inhertience so it does not take from any blizzard melee data. You then can remove the dependency of the map on blizzards melee data and as such dramatically optimize map loading as it will not have to parse all that extra data. This is what blizzard has intended us to do, so that custom melee maps and such will not use any SC2 melee data (might share art work) thus load more more efficiently.