I don't use this exact combination, but I have used the GMajor and other MIDI type preamps.
What you want to do can be done, it depends on the MIDI foot controller you are using. I am assuming it is the FCB1010 which I have used.
You have two options. Either have the 1010 send to Program change messages on different channels and assign the Triaxis and GMajor to listen on different channels. Or
I am pretty sure the GMajor has the ability to map PC1 to preset 2 (a MIDI mapping capability) so you can send 1 PC message and have it set both at the same time. I opted for 2 PC messages and each listening on a different MIDI channel.