Category question

I installed Maian PAL recently (Love the beasty and sent in a Dutch language pack for it).
However, one thing bothers me a little bit: is it not possible to take the subcategories to deeper levels?
I'll explaina bit further: I sell music for Accordion, and I sell sheet music and the mp3 of that sheet music.
I have separate categories for the PDFs and the MP3s, so far no problem.

But then it happens:
I have posted some ordinary music, but also some study material, so I made a category for that, and I wanted to subdivide that category again in "Beginners", "Intermediate" and "Advanced", and that Maian PAL won't allow me to do.

Could anything be done about that, or maybe an idea for a later release?

Thanks in advance. smile