Adding the ability to create subcategories in the House Manual would help organize the cards a lot. For example, it would be nice to have a subcategory for the Kitchen since several cards will be for operating kitchen appliances - having them all in one place would be cleaner and easier to find for the guest. Having a subcategory for Bedroom, Living Room, Yard might be some other options hosts might want to create. I envision the subcategories to be near the top of the manual, similar to subfolders in a directory. I know a workaround would be to create custom categories, but I'd rather keep everything under "House Manual" than adding new categories to the list of icons.