You are calling the FC (Foot Control), "CC". While the Foot Controller 1 and Foot Controller 2 Send CC messages (Control Change) messages, by referring to them as CC reading your post makes no sense.

If the Foot Controller 1 is set (as the default) to send cc11, by definition in MIDI it will always control Expression (which is performing Volume). No matter what else you tell it to do cc11 will always affect volume.

If the Foot Controller 2 is set (as the default) to send cc04, by definition in MIDI this is Foot Control. This would be the wise decision when you want the Foot Controller to function as something OTHER than Volume. For example, when you want it be a Wah-Wah for the VCM Pedal Wah.

CC 11 is a fixed function in midi
Like Pitch Bend... you can assign other things to the PB wheel, but expect it to always send Pitch Bend in addition.

CC 4 is not a fixed functions... you can decide on a per Performance basis what it will do.
Like the MW... you can assign anything you want to the MW - it doesn't not have a fixed function - you must give it one on a per Performance basis

Sorry, read CC as "continuous controller" to differentiate from switch (on/off) controllers. My bad.
So from what you have said, I can re-assign FC2 (which by default is CC4) to function as an expression pedal in some performances? Surely I would need to remap to CC11 somehow.
Basically what I want to do is avoid having two pedals for different functions, I'd like to use the one pedal for expression in some performances and control the VCM wah in others.

Basically what I want to do is avoid having two pedals for different functions, I'd like to use the one pedal for expression in some performances and control the VCM wah in others.

Plug your FC7 Pedal into the Foot Controller 2 jack. Since it defaults to cc04, you get to define what it is controlling on a per
Performance basis. You can set to be Volume when you need it, you can set it Control Effect parameters when you need that.

See page 21 of the CP4 Stage Reference Manual

For a tutorial on setting up the FC7 in the CP4 Stage, please see the following article. Post back if you have other questions

A Closer Look at the VCM Effects: TOUCH WAH/PEDAL WAH

One of the options for the pedal is "volume" so you can assign the pedal (cc04) directly to control the Voice volume.

Great, that makes sense. I'll try it out. Thanks