POWER OF ATTORNEY QUESTION

I AM MY MOM'S POWER OF ATTORNEY AND POWER OF HEALTH. I HAVE FOUND OUT THAT A FAMILY MEMBER TALKED MY MOM(HAS MODERATE DIMENTIA) OUT OF 15,OOO. WHAT ARE MY OPTIONS OF MINUSING THIS MONEY OUT OF THEIR PORTION OF MY MOM'S INHERITANCE. THEY WILL NEVER PAY HER BACK.I KNOW THAT. THAT FAMILY MEMBER DOESN'T KNOW THAT I KNOW ALL THIS. I DO NOT WANT TO BRING IT UP TO MY MOM WHILE SHE IS STILL LIVING . IT UPSET HER ENOUGH THAT THIS FAMILY MEMBER EVEN HAD TO ASK FOR IT. THE REASON SHE NEEDED IT IS WHAT UPSETS ME. ANY HELP WOULD BE APPRECIATED