Are you sure? I thought the private creditors were already "haircutted", most of the Greek debts is to EU states and IMF.
Smaller creditors were stiffed. Foreign Goverment entities were exempt and foreign institutions (pension funds etc) could buy at 30-40% percent the defaulted bonds. Said foreign Governments had ofcourse the inside information that they would give the Greeks the money to repay in full price their debt. That was hidden from the other investors during the start of the program.