3D Compositing with Action > Action: Sources > Creating a Matte or Front Source >
Parenting and Redrawing Source Nodes

A source cannot be parented by other objects in the schematic. If you attempt to parent a source, the connection is refused. You can, however, parent objects inside a source node and they appear in your scene based on the Source Type settings in the Object Image menu.

NoteBe careful when you unparent or delete a source. Surfaces or other objects that were parented by the source are added to the scene.

See Parenting Nodes.