Importing a Skeletal Mesh Hierarchy
If it is a Skeletal Mesh you wish to manipulate with the Control Rig system, the quickest way to get up and running is to import the Skeletal Mesh Hierarchy into the Control Rig Blueprint.
To do this, right-click in the Hierarchy panel and select Import. From the Import roll-out menu, click the None drop-down box and select the Skeletal Mesh hierarchy you wish to import.
The system will automatically create the Hierarchy based on the Skeleton associated with the selected Skeletal Mesh. The naming convention can be set in the Control Rig window of the Mesh Editor (Window > Control Rig) which enables you to configure the mapping configuration for the selected Control Rig.
After importing a Skeletal Mesh, the Joint Hierarchy for the mesh will be displayed:
Right-click on a Joint to provide additional contextual options:
In the Joint context menu, you can add a new Joint as a child of the selected Joint, delete the Joint, duplicate the Joint, rename the Joint, or import additional Meshes to add to the Hierarchy.
After importing the Skeletal Mesh and generating the Hierarchy, you will need to assign the Skeletal Mesh as the Preview Mesh to see it inside the Viewport. You can do this from the Preview Scene Settings tab.
After importing your Skeletal Mesh Hierarchy and assigning the corresponding Preview Mesh, you will want to click the Compile button to compile your Blueprint. This will enable you to properly get a reference to the Hierarchy you have created inside the Rig Graph where you can start to manipulate the Joints with Rig Units.