Illustrator CS6 cannot change the weight of characters without unicode


I’m adding icons to the font. Since some of symbols are not in the Unicode (burger menu, diagonal double sided arrow), they had to be without unicode. They export, but Ai treats it like it’s from a different font, so you cannot change the family or weight (app thinks multiple are selected). There’s no issue with InDesign though.

Is Unicode’s Private Use planes the solution? And if yes, do I just assign random numbers from there? I know Apple used Private Use for San Francisco.