I have not been able to find a way to bulk rename files other than the option that completely replaces the existing name.
I use a free utility, Bulk Rename, which can be downloaded at:
http://www.bulkrenameutility.co.uk/Download.phpI am running Win7 64-bit so I installed both the 32-bit and 64-bit versions of the utility.
In TP7 I am able to add Bulk Rename as an external program placing an icon on the toolbar. In the external setup, I picked the option to pass the folder name. Passing selected files to Bulk Rename does not seem to work. Of course the downside is this procedure does not update thumbnails. So, after Bulk Rename I have to delete orphans and create new thumbnails. In TP9, I cannot get the external program feature to work with Sqlite database. So, I use Bulk Rename to rename the appropriate files, then start TP9 and delete orphans/create thumbnails.
Hope this makes some sense.
Gary