>>/29084/
Subunits can be moved around freely (and passed on as detachments) without disbanding the unit itself and keeping the HQ "alive". And the HQ can have units "de jure" but the unit "de facto" belonging to other units.
Ifc HoI getting inspiration and many facts from reality, but the developers had to standardize since reality is very complex. A size and organization of a division was different in one country and another, and this discrepancy could go as deep as squad level. Or the the lowest independent unit was the brigade in some countries (liek in Hungary), and so on. Ofc in this question the French organizational practices would be the deciding factors.