It seems that every description providing ways to visualise or form analogies or presernt a simple model for infalling to Black Hole causal event hortizons rely on two observers, one aporoaching and potentially 'crossing' the horizon, whilst the other 'observes' from a "safe" distance. It makes sense of coursr, to have just Alice and Bob as the two intrepid BH experimentalists, for the most simplistic and readily understandable/accessible picture of the potentially paradoxical consideration of when or even if the infalling event occurs at all. Yet despite adding a necessary amount of complexity, considerring just oner extra observer should reveal a much richer description. For instance, since the time dilation effect increases to limit on approach to the Horizon, then even an accelerating Charlie trying to catch up with Bob as the latter continues towards the Horizon, will never reach either since Bob will always be in the distance despite slowing down - To me, and this may require correction and/or further clarification, the distance to the Horizon will appear to increase regardless ofg Charlie's motion towards Bob? Alice will 'see' Bob redshifted and slowing until fading from view before the horizon, but will she notice Charlie catching up to Bob or never getting closer? Admittedly, this is similar to the consideration of just observing as Bob heads to the Horizon, but I think with Chartlie's frame of reference considered and a cave that possibly even for Bob's perspective, there will always be something (especially light) that will be moving to the horizon beforehand which I am under the impression should necessitate a 'prevention' so that nothing can actuially experience crossing the Horizon. This 'road block principle' also helps eradicting certain paradoxes, but without a holograpghic BH would mean that BH couldnt actually accept any more matter!