If the car is on its jacking points the suspension will be hanging free, so nothing will happen.
You need to have the wheels on blocks/ramps with the rear suspension compressed carrying the weight of the rear end before moving the linkage will do anything I think.
You just need to have a good amount of clearance between the underside of the car and you, so if the rear end drops you are safe...

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2009 Mercedes ML320 Bluetec