YAHOO Group Owner/Other Moderator is "Hard Bouncing"?

There are 3 owners/moderators and I am one of the moderators. The Owner and Other Moderator have had their YAHOO accounts discontinued. How do I get the old Owner and other Moderator removed from the Group since they no longer have a valid YAHOO ID? How do I get my status upgraded from Moderator to Owner so there will be at least one Management person functioning in this Group?