Hello Julian,
Hauptwerk doesn't currently have 'divisional coupler' functionality for its scoped combinations (or anywhere else, unless the sample set provides that functionality itself), although it is logged as an enhancement request.
You could certainly scope any given scoped combination to affect two divisions simultaneously, but you couldn't then 'de-couple' the two divisions with a virtual switch/piston.
(You could conceivably implement some functionality yourself within MIDI encoder hardware to couple/uncouple MIDI pistons, i.e. so that either or both transmitted MIDI messages, depending on the state of a hardware switch.)