Maryanne is next oldest after Fred Trump Jr, who didn’t like his father’s business and died young of alcoholism. Maybe Maryanne thought she should have been the heir of her father’s business.
“...Maybe Maryanne thought she should have been the heir of her father’s business....”
Pretty much says it all, right there. A lot of these “sibling issues” (the ones that aren’t drug-infused) are money/business/inheritance issues. I’ve seen it over and over with immediate family and friends. “Follow the money trail” seems to apply to sibling/family issues as well. Money changes people....and hardly ever for the better.