I have an iPad 4 with an extensive book collection which I have been able to organise well. Just got a retina mini for easier bedside reading but cannot add a new collection. it picked up some of the authors I had when I loaded iBooks and listed them under collections but how do I modify this list. It seems I can delete the authors but not add them. Nor do I seem to be able to create new categories. I can't imagine Apple dropping these features on iBooks. Hesitate to upgrade my iPad 4 to ios7 in case I lose my sorting ability. Any thoughts?