Gcx help

[Nomis56]

Hi everyone,
I have a question in which I have not be able find the answer.
So basically I have an orange rockerverb 50 mkiii which I can get everything to work fine with the Gcx and ground control pro, pedals, channel switch etc.
But my question is I also have a preamp that from time to time I like to run through my effects return and bypass the preamp on my orange.
So is there a way that I can set up the gcx/ Gcp so that I can use my orange as normal and also run the preamp through my fx return and basically A/B the two of them.
Sorry if this is confusing and thanks to anyone that looks at this post.
Cheers.