I must confess I don't understand the point you are trying to make but, let's play!!!
According to your own rules we must stick to syntax even though we can turn to semantics here and there, so there we go...
We are having our house redecorated.
are having (verb)
our house (object)
redecorated (object complement, though I think it complements the action not the object, but OK, so far so good)
However, this sentence means something like,
'A group of professionals is/are redecorating our house (for us)' and so, we can see
We (subject?, it means something like 'us'; it is a subject because it happens to be placed before the verb, keeps concord with it and it is in the subjective case)
are having (verb, active but with a passive meaning)
our house (object, ok, but it would be very difficult to explain why the object remains the object when the verb has a passive meaning)
redecorated (object complement?, that would be debatable with 'had' or 'have had' but not with 'are having'. The information conveyed relates to the process not to the noun; passive meaning, again)
To me this is Quirk at his best!!!. He would admit an implied (elliptical) subject in 'Stop', (for example), but would not admit to the existence of different kinds of subjects just because for him a subject is a syntactical constituent that has nothing to do with meaning. 'We' in this sentence may look like a subject but it is not the real subject, just happens to meet the requirements established by Quirk to define a subject. That's Quirk.