Boiled cider is just apple just that has been reduced, usually about 8 to 1. I am thinking of adding boiled cider to apple juice and trying to ferment them together to raise the sugar content of my juice. Has anyone done this. FYI I own an apple orchard and i have plenty of juice to experiment with. I also make my own boiled cider. https://www.amazon.com/W-C-M-Boiled-Cider/dp/B00DUF2SWA