I believe I've read that one can actually create subfolders unders the Documents folder on the K3 and the K3 will still list all of my books (in other words folders under Documents would not "hide" any of my books). But I've already created nine collections and did not really want to ruin that work if moving items from Documents into subfolders would screw things up.
And the reason for creating subfolders at this time would be to add a bit of organization - the Documents folder with all of those books is just a bit too disheveled and is growing more so.
And, yes, I can experiment, but if I get a timely answer I won't have to
Thanks in advance.