many-to-many mapping of users to apps!

I need a many-to-many mapping of users to apps. In the HQ environment you can DUPLICATE apps from one WORKSPACE to another, but I want to instead LINK the same app to multiple HQs, editing it just in MY workspace. (I need apps A, B, C and F accessible to Group 1, and apps B, C and D accessible to Group 2. Can this be done with HQs? Duplication isn't the right approach, because it forks the version, making hand-edits necessary for every clone.)