Oh Boy, that is upsetting...it could have been worse, a moneyorder can easily be cashed by him, no matter who it is made out to...I learned that the hard way.
Personally I would tell your parents, at their age they do not need any more surprises, I wouldn't cover for him, and let him try and play catch up...maybe your parents would better understand the con jobs being played on them and
stop enabling him.
Don't know, just my thoughts.