A axis on Black Box

Thanks to Peter Van Der Walt for pointing me to the Blackbox which answers my question for a controller which I can use open source software to run my hobby cnc. But I did do some research on grbl and if I read it right it does not support a rotary attachment. On the black box I saw 4 axis attachments X,+Y,-Y, and Z. I was wondering if it would be difficult to change one of the Y axis to run the rotary attachment or basically a A axis?

I am not new to software or had not before my stroke. I kinda forgotten alot I use to play around with RedHat a long time ago .

 

Thank you.