Help really needed here as the manual is making no sense to me at all.

I'm wanting to use both the mic attached to the cam for recording ambiance, at the same time I'm using a microphone connected to the rear of the cam via the XLR connections.

I set the camera's audio to 12 bit 1/2, 3/4 channel set up, but no matter how I set the switches on the audio panel am I able to record sound from both mic's at the same time. It is only one or the other depending on the switch selector on Audio 1 Front mic or rear.

Is it even possible to do this?
And yes, the XLR mic does need phantom power, and the switch is set to suit.
Please, please tell me how to do this.

Thank you