Mythtv - slave backend using NFS root question

[usg990a]

I am currently running a master backend for Myth that also contains the root fs for the frontend. I recently added a STB Firewire tuner to the frontend which required making it a slave backend/frontend combo. The box PXE boots with root over NFS. I can record from firewire (which storages the recording physically on the master backend) without issue.

However, mythfrontend now reports 2 drives (in system information section) which effectively doubles the free space available since the same directory is used (although the % used / free is correct). Below I have listed the structures for directories. My question is how can I set this up better so that myth only sees one drive with the correct amount of space available / used.

Master backend:
350GB partition mounted as /storage
recordings are placed in /storage/video locally from Hauppauge PVR-150

Slave backend:
NFS root from the master backend on separate partition (/diskless/downstairs on master)
NFS mount /storage from master backend (i.e. /storage on master is NFS mounted on slave as /storage)
recordings are placed in NFS mount /storage/video (same physical location as master backend)

Myth sees it as two drives (master:/storage/video and slave:/storage/video). How can I set it up to only see it as one drive?