https://learn.microsoft.com/en-us/windows/win32/api/msopc/nf-msopc-iopcrelationshipset-createrelationship
IOpcRelationshipSet::CreateRelationship (msopc.h) - Win32 apps | Microsoft Learn
Creates a relationship object that represents a specified relationship, then adds to the set a pointer to the object's IOpcRelationship interface.
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