When using constraints, how can I get a child to have two parents? I have tried a myriad of ways to get a child (ArmC) to have two parents (RivetD and RivetC) but I can't get it to work.

Now I realize that there are ways to "fake" constraints so that they look like they work, but for this question, I am trying to figure out if the Blender constraint system can drive objects with multiple joints like they really would function in the real world.

When rotating ArmA which drives ArmB, is it possible to have ArmC stay secured and rotate at RivetD while at the same time staying secured at RivetC which would then cause ArmB to rotate differently?

Here is the blend file:
https://dl.dropboxusercontent.com/u/6647893/Forum_Help/TwoParentConstraints.zip

This is an example of what I am trying to accomplish:
https://dl.dropboxusercontent.com/u/6647893/Forum_Help/Angles.jpg
This is a typical Inverse Kinematics job, is this what you are trying to accomplish?
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