wxlocal.html will turn into wx.html by WD and that is what you need to set to create and upload, create and upload are two steps in Internet File Creation and Upload and in the Upload settings box at the top is a box named “Remote file name” that is where you would set wx.html to change to index.php.
However another way is to let WD create and upload the files in their default named state and simply include them in your PHP pages which allows you to build the pages around the content.
-Bob