My 60 year old sister-in-law spent quite a bit of her life with her parents involved. When my mother-in-law passed, my blind father-in-law came here. We took care of him, she took care of his money. On a regularly irregular basis she would pick my father-in-law up to spend a weekend at her place.
After two grueling years, we learned she had taken all his money and charged up his credit card to the hilt as well! She was also in the background encouraging him to express his anger and was successful during this time in turning him against us!
So we've been completely holding the bag and we're miserable. There is also a son whose self-importance keeps him from helping who lives around the corner from our home.