Climbing Multipitch activity

I'd tell you can use the standard climbing for that. If not good enough, use the Multisport feature to combine several climbing activities into a single multisport activity. You can also combine it with hiking for the descent, if needed. Navigation can be used anytime, regardless whether you are in climbing, hiking, or in another outdoor activity.

yeah, that can be said about triatlons or many activities. 

in multipitch you can preload a route, it would potentially detect each pitch (if you are swapping), tell you even if you are off route. (by gps). 

Yes, exactly. You can do that with climbing too. You start the activity climbing, then you start the navigation of the course from it. You do not need any special mulltipitch climbing activity for that. The climbing activity, or the navigation in no way limits you to a single pitch. And if you really want to split the individual pitches, and the descents, then use the Multisport feature, as I wrote (Stop » Change Sport). The same course may stay running in the background the for all parts of the multisport activity.