You can insert, move, hide, or delete tracks in multitrack clip groups, but it may break the clip group. A separated clip group displays a break in the Clip Group icon. Separated clip groups will continue to function as a single clip group, but the separated icon indicates that the clip group displayed is somehow incomplete or separated across nonadjacent tracks.
There may be situations where you want separated clip groups. For example, if you use the same accompaniment on verses one and two of a song, you can group the parts of verse one and copy them as a clip group for verse two, but still have a continuous vocal track in the middle of those clip groups.