Ah yes. That's a continuity error. Considering it's Season 10 DVD (where Bobby and Katherine never died) rather than Season 9 DVD where Katherine and Bobby were both dead and Cliff would have inherited some of Wentworth Tool and Die if Katherine had died intestate, it makes no sense. The brass obviously forgot that Cliff had sold his share of Wentworth Tool and Die to Katherine in Season 7 DVD, even if she was later a fugitive after skipping bail for attempted murder of Bobby. Legally, it would still be Katherine's, and she made it clear that she would never sell it back to Cliff.