Acting-up and interim appointments: do they count at the acting level, or sit outside it?

I work for a provincial government agency in Canada with about 2,100 employees. At any time roughly 160 people are in acting assignments one level up, with acting pay, and a fair number have been acting for over two years because the substantive position cannot be filled permanently during a hiring freeze.

Our framework says nothing about them. They are recorded at their substantive level, so our level distribution, our career path data and our pay equity analysis all describe an organisation that does not quite exist.

Do others report people at their acting level, and is there a point at which a long acting assignment should simply be treated as the level?