I get what you mean by the fact that it was also the vision of other ME writers and of course the actors contributed as well

Well in this case other writers are contributing so that is like the tv show

Has for no actor contributions well there is events in the tv show that we were told happened ,like Xanders adventures between season 3 and 4 or implied happened like Spike hooking up with Harmony (in early season 4 ) that we accept as canon