When I'm trying to do 3D Body Tracking, how do I create attachment points for my model of a jacket?

In the "Two Spacesuits" example the attachment points are connected to the physical spacesuit. How do I create attachment points for the jacket I created? Where do I do that? I think this is the correct way to make sure the jacket moves with arms. Right now, it only resizes and moves with the trunk of a person's body, but the arms do not align. I assume because it has no attachment points.
So, how do I create these attachment points for a jacket?

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