I was thinking that perhaps the "someone is here" that D heard was X trying to wake up E from a deep sleep (which would make her distracted enough for BK to come up and grab her without much noise), but your comment that it could have been in reference to the Door Dash is something I hadn't thought of. As quiet as this was, though, I really think that E was asleep, as I imagine BK going against two at once would produce a bit more of a commotion.
***Edited to add that the "your comment" was in reference to post #310 by
@alex dvport . The post didn't include the quote for some reason!