Load/merge a show file onto a host theater's Ion and preserve their channel patching

Yes you can. This can be done 2 ways. Either merge their patch into your file by using the merge function in the CIA and selecting only patch or you go the other way and merge your file into their patch. We often have touring shows come through where we have a prerig which is different to ours so once we patch and flash we then save the file. when the tour arrive we load their file and then merge our patch in and off we go. 

This is of course if you use their channel numbers in your show file.

Yes you can. This can be done 2 ways. Either merge their patch into your file by using the merge function in the CIA and selecting only patch or you go the other way and merge your file into their patch. We often have touring shows come through where we have a prerig which is different to ours so once we patch and flash we then save the file. when the tour arrive we load their file and then merge our patch in and off we go. 

This is of course if you use their channel numbers in your show file.

This gives me confidence! I'm hoping I can actually try it on the offline software as a learning exercise. Thanks.

Yes of course you can do it in the offline software. After all it is the same software as on the console. Using the software on your computer is a great way to learn. It is how I learn and try new things when I have a little down time.