Insert a Remote Point, Behavior=Deformable, scoped to the faces or bodies on the part of the structure you wish to monitor. A single point will be created at the center of gravity of the scoped nodes which will average the motion of all the nodes on that part of the structure. In the image below, I have one surface I am monitoring that is supported on another part that I don't want to include in the monitoring.
Use a Deformation Probe.
Use three Flexible Rotation probes.