Panel merging: what's the basic principle?

Hey folks,I've been looking around and seeing how panels are merged. I always thought it was a standard procedure of copying the panel folder to your new aicrraft, but I see there usually are more steps behind it. Do note I'm talking about merging complex panels with other aircraft, such as a PA Airbus with a Wilco Airbus panel, that kind of stuff. What I want to know, is if anybody can give me the basics of what you do when you merge such a higher quality panel with an airplane that usually has a much more simple panel. Of course, I do want stuff like autopilot, APU and all that stuff to work proparly in that enw airplane. I suppose that it'd also be good to know why some panels merges are difficult or don't work at all.If somebody can answer these questions, I