The Attach command makes
the selected object part of an existing assembly.
With an object selected,
choose this command, and then click either a closed assembly in
the scene, or the head object of an open assembly.
To attach an object to an assembly:
- Select one or more objects to attach.
- Choose Group menu Assembly Attach.
- Click any member of an assembly.
The selected objects
become part of the assembly, which is now selected.