Creo Illustrate should have the option to Publish Separate Files directly to Windchill.
When creating an Arbortext documentation, for example, these separate figures can be used as Windchill objects in the Structure but it is impossible to get these figures to Windchill without WGM and Workspace import functionality.
Saving the illustration c3di-file to Windchill does contain the separate figures, but the figures can not be used independently in Windchill structures
