[Answer]-How to combine an admin module from different ModelAdmin

Depends on the constructs of the objects, but you could try (might cause clashes):

class MyGuardedOSMGeoAdmin(GuardedModelAdmin, OSMGeoAdmin):  # or visa versa
    pass


class MyAdmin(MyGuardedOSMGeoAdmin):
    # your declarations


admin.site.register(MyModel, MyAdmin)

Detailed information on (multiple) inheritance can be found here