How to animate shape keys without duplicating mesh data block

I’ve searched high and low and found nobody correctly (aka “working” in recent blender) explaining how to do this problematic situation:

  1. A Mesh Data object (let’s call it ‘mesh1’) containing shape keys
  2. Two objects in different scenes (let’s call them ‘object1’ and ‘object2’)
  3. Each object shall play back different sequence of shape keys

First things first the stupid shape key data is mesh-data-block linked and thus the source of the major headache.

I’ve tried using a rig to drive the shape key depending on bone position but this does not help since the driver is assigned to the shape key position and thus mesh-data-block linked (arg!)

Then I tried using a proxy object since somebody claimed by proxying the rig this should work. For this I created two files, one with the ‘mesh1’ in it and a ‘object0’ and one with the ‘object1’ and ‘object2’ in it whereas ‘object1’ and ‘object2’ are proxies of ‘object0’. I can animate the bone and the driver does change value BUT the shape key position does NOT take over the value.

I’m at a loss how the hell this is supposed to work. Why is that stupid shape key selector not an “object” parameter? Obviously this is a total design fail.