I found a solution. A-PDF Content Splitter worked. I'd tried other splitters (including the one bundled into Adobe Acrobat XI Pro) but none worked the way I needed. I downloaded a free trial of the A-PDF content splitter I just mentioned and it was easy. I chose the textbox that contained the text that would change anytime I wanted a split and voila, it did it. The crucial part is to name the output files with that text string, which it does. Price to buy : $79. I googled for a coupon and got it for $51.