Owner-Content relationship for WTDocument

When associating EPMDocuments (CADdocuments) to a WTPart, you have to define the nature of the association, e.g. 'owner' or 'content'. Has someone customized/implemented a similar concept for WTDocuments to WTParts? E.g. via a 'Describes' link, where a WTDocument revision can only have one 'owner' link, but several 'content' links.

TIA, Hugo.