I'd like to get this clear in my head before our game starts. First, a little background/group composition. We have a Storm Warden Librarian, Blood Angel Assault, Blood Angel Devastator, and a Dark Angel Apothecary. Now, so I'm clear, only the Blood Angels will benefit from using their Chapter specific attack and defense patterns, and only those two can enact them (providing one or the other is the Kill Team Leader) correct?
If this is the case, what is the use of having a mixed batch of Marines? Wouldn't it be better to have members of a kill team be all from the same Chapter? After all, that would open up all Attack and Defense patterns available (or, at least, you'd have access to one more attack pattern and one more defense pattern that if you had a mixed bunch of Marines.).