Do you have any more info? AQHA shows 138 mares who have a name beginning with Calypso. If you take away mares born prior to 1985 and those born after 2005 there are only 50 possibles, so it might be worth tracking down.
Who knows, maybe the breeder has calmed down some and would be willing to sign off if you get the ball rolling. I think most people would agree that APHA papers are more valuable than PtHA papers alone. It is something that I wouldn't give up on.