So here is the new arrangement. It's my main MDFS with its usual four expansion boxes underneath, with the new Domesday Box on the top. The usual boxes have been disconnected from the back of the MDFS and the new box plugged in instead. I couldn't run all the boxes at the same time because all the drive letter allocations in the MDFS have been used up by the existing boxes so it is a case of unplugging these whilst the Domesday Box is in use.