I am wondering if it would be a big job to add plus signs (+) in the card-creating categories to indicate sub-divisions (similar to the sub-categories shown in the left-hand category columns for customers). If it's not a huge undertaking that would divert too much energy and effort from more pressing concerns, I think it would be a very helpful refinement.
 
Thanks for considering it!

We'll see what we can do.  Thank you for your suggestions.