My boat has three TZT3 displays, two 12 inch units, labeled as port and starboard and a nine inch unit in the lower helm. Currently, the 12 inch Starboard unit is set as the master chart unit. I recently purchased a memory card with CMOR charts. I would like to install the card in the lower helm 9 inch due it being much easier to access. Do I need to set that lower unit as the master in order to access the CMOR chart from my upper helm port or starboard? Also, if I primarily use the starboard unit for charts, is there a speed advantage for having the card in that particular unit as opposed to having to access the card from a different unit on the NMEA 2000 network? I appreciate any helpful information, thanks