You can mix the MLS and QLS forks/receptacles.
For your application here is what you'll need:
You'll mount the QLS Receiver Plates to each of the MLS forks using the splined attachment holes on each. These two combos will allow you to mount the holster to the PALS webbing on your belt and PC at whichever angle you need.
The QLS fork will mount to the back of your holster.
Now you can swap your holster between your belt and plate carrier using the QLS fork/Receivers while being attached to PALS webbing.