Using WinUSB to communicate with Identical WPD devices.

I have the WinUSB docx file and the procedures it outlines are clear. However, I have multiple identical USB devices, all using the MTP USB Driver set which is installed when the device(s) are connected. I cannot change this driver as it is used by another process which runs when the program I am attempting to write is not running. These are all installed with the same inf file so will have an identical GUID number. My problem is to differentiate between these devices in order that I can get a handle for file transfer from the selected device. The devices return different serial numbers using the WPDInfo.exe in the driver development kit using WPD_Device_SERIAL_Number which would be a one approach.

Any help much appreciated.

Best Regards

picclock