I have the same situation, I want to use 3 HBAs per blade, the second mezzanie card maping to bay 5 and 6.
I moved the 20-port FC module from bay 4 to bay 5. still only 2 HBA connect downtrean to server.
Any resolution on your end?
seem like a waste have to buy additional FC module to fill bay 4 , when we have 6 unsue empty FC ports.