Myth:Auth extended permission check

Hey guys,

in a project we are starting now there is a bit of a awkward permission check requirement. Each users permissions are different depending on what operations he wants to perform on which "object" - where objects are dynamic from another database. IE one user should have a "view order" permission for one store, but is not granted that permission for say another store. 

Heres the tables as drawn in the project specification: 

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LogisticsClients (or stores) are essentially groups (which the myth:auth supports) but they are dynamic, and its not convenient to add say 10 groups for each client that appears.

I really wanted to use Myth:Auth for this project, since it handles an enormous amount of jobs. Do you have any ideas how can i extend the Auth lib, or how can i workaround this situation so that i can still use the  library but achieve the result needed