Markus-
You bring up several valid objections against my argument, and I'd like to respond to them:
1) You state that Brehm, Hill and Moorman would have heard the shots fired from BL_1. I don't disagree with that statement. Here's the thing: I am saying that BL_1 was an assassin - if that's true, the conspiracy plan MUST have included some support and/or cover for BL_1. It would have been very shortsighted to simply place a gunman out in the open all by himself with no further consideration. With that being said, I think that Brehm, Hill and Moorman were assets for the conspirators. Consider the following:
a) Look at the Z-film. Brehm is almost perfectly placed to mask BL_1 from view - from the perspective of the Z-camera. He is also blocking BL_1 from being seen by anybody in the street. Personally, I am inclined to think that the SS agents behind JFK were all in on the plot. But if it was the case one or more of them were not, then Brehm would have shielded BL_1 from being seen by them.
Furthermore, watch the Z-film and note that Brehm and his son were clapping their hands. This would serve as sonic camouflage to cover the sounds of the (silenced) firearm from BL_1.
Also, people (such as William Newman) have reported gunshot sounds coming from the grassy knoll. I think the conspirators placed people there to fire blanks, which would have distracted and confused bystanders from focusing on BL_1 as he fires his weapon.
b) Keep in mind that dozens of witnesses have reported that JFK's limo came to a stop. Where did it come to a stop? According to statements by William Newman, who was on the north side of Elm Street directly across from Jean Hill, the limo came to a stop right in front of him, and that's where the fatal head shot occurred. Here is a statement from longtime assassination researcher David Lifton (from 'The Great Zapruder Film Hoax'. pg 424):
In November, 1971, I went to Dallas for the first time and had tape recorded
interviews [with] Bill and Gayle Newman, who were directly to Kennedy's
right when he was struck in the head, and who insisted that the car came
to a momentary halt, right in front of them.
In other words, the fatal head shot occurred at a more easterly location on Elm Street than that shown in the Z-film (Z-film was edited to mask the limo stop - see 'The Great Zapruder Film Hoax'). When you shift the foreground (JFK's limo and the DPD motorcycle officers) of the head shot frame (z313) further east, it is apparent that BL_1 would have had a clear line of sight to the back of JFK's head.
c) Jean Hill, dressed up to look like a giant stop sign, would have served as a marker, obvious to the limo driver and BL_1. The limo driver brings JFK to a stop right along side Jean Hill, where BL_1 will be waiting to administer the kill shot.
d) Mary Moorman's role was to have provided photographic 'evidence' to support the Z-film. I go into much greater detail on this point in an ebook I wrote on the subject - a free pdf download at aninspiredbitoftreason.wordpress.com/.
2) You mention that BL_2 must have been close by somewhere - but you are unable to locate her in any photos. I can't locate her either, and believe me, I've tried. How about this scenario: BL_2 was in a vehicle some distance behind the JFK motorcade. Very soon after the assassination, the vehicle pulls up to the curb on Elm Street and lets BL_2 out, and BL_1 simply starts walking away (as I demonstrate with my analysis of the Bond 8 and 9 photos earlier in this post). Such a transfer would have taken 15-20 seconds, tops. And, in the chaotic aftermath of the shooting, who would have noticed?
3) You call into question my fundamental premise that there were two different BL's: one present during JFK's murder, and a replacement soon afterwards. We are just going to have to agree to disagree on this point. Earlier in this post I put forth all the evidence I was able to muster in support of my argument. I have nothing more to add on this point. If I did, I would post it here. I just want say that I am adamant that BL_1 and BL_2 were two different people. If I didn't really believe that, I wouldn't be writing these words...
At any rate, I appreciate your thoughtful objections. It is only through back and forth discussions such as this that we can come to some understanding of what happened in Dealey Plaza that day. Clearly we can't rely on 'our' institutions (media, law enforcement, judicial, etc.) to tell us the truth - it's up to us to dig for it...