What Was The Role of David Herold

[Gene C]

Is it possible Booth spoke of "others" in an effort to encourage those who might be waivering in their dedication to his cause, by making the number of conspiritors larger than it really was?

As for these unknown "others" on the fringe who are seen acting strangely, in most notorious crimes there are usually eyewitnesses who see things that never were, and see suspicion in ordinary activities. Kooky witness come out of the woodwork to report strange things they've seen.
(Either that or I've wasted years of watching TV cop shows.)