Ultramel is it's own thing, they're not compatible with caramel. It's simple recessive and has none of the issues associated with caramels; kinking or breeding issues. I've never seen one IRL but I know they're supposed to look much different than caramels side by side. Imo ultramel is hotter.
Soooo they aren't compatible. That makes me think they're kinda related or something? Or is it just like 2 different lines of hypos that aren't compatible with one another?