WDM 5 - issue re-imaging existing D90D7 devices

I have inherited a WDM solution of 100 D90D7 devices and a WDM 5.0 server - but no documentation !!  I've managed to learn how to image and re-image a device (or group of devices) and how to create a new image, however my new image requires some manual intervention after the re-image to format the second partition (D drive) which was present in the image before I uploaded it into WDM.

the original image I inherited has this same issue and I based my image upon it as a starting point.

Is there any way to automate this (or to make it happen ?)  so I don't have to manually edit 100 devices ?

thanks