It'd be great if instrument tracks could behave the same as audio events insofar as when you split and then move or copy a section of an event, the copy will contain all the data as the original which could be revealed if trimmed back or forth. Many other DAWs work like this, however, the only way to get an instrument track to work like this is to move the whole part. If you split the section you want and then move it to another area of the song, you are unable to trim forward or back to reveal other notes from the original (however cc data is able to be revealed).