Re-define the parent of the selected rigging component. To use select the component you want to re-parent and the new parent object. This is saved when saving a rig file and the component will be parented to the chosen skeleton joint whenever the rig file is applied.
Re-creates the parent constraint that connects the top group for the rig component to the skeleton. If Bake Component is checked in the User Settings the rig controls will be baked to preserve their world space animation under the new parent.
The new parent can be either a skeleton joint or a rig control, if you select a rig control the tools will automatically find the skeleton joint that the rig control is driving.