Yet More Intricacies Within The Never-Ending Subject Of Time Travel

In Poul Anderson's The Shield of Time (New York, 1991), four Exaltationist time criminals plan to change history by helping King Antiochus the Great of the Seleucid Empire to defeat and kill King Euthydemus of Bactria:

"'If necessary, energy weapons. I hope, though, that Antiochus will dispose of his rivals in a normal way.'" (p. 89)

I had imagined one Exaltationist shooting Euthydemus and possibly, although this was not their intention, leaving his three companions behind in the "deleted" timeline. However, if all four are involved in the sequence of events that causes Euthydemus' death, then I suppose that this will carry all of them forward into the new timeline?

Another Exaltationist comments that:

"'[The Patrol's] remnants downtime will not vanish remember...They will not be negligible. The fewer clues to ourselves we leave, the safer we will be, until we have grown too powerful for anything they might attempt.'" (pp. 89-90)

The point is that some Patrol agents returning uptime from pre-209 BC will realize that they are in an altered timeline and will try to rectify this. However, we already know that most, maybe all, Patrollers returning uptime enter the future of the timeline guarded by the Patrol.  If all, then I argue that there will be no one to oppose the Exaltationists in their new timeline but that this will not matter to Patrol members, who will be unaware of the changed timeline. If some Patrollers find themselves in a powerful Exaltationist-controlled regime in what should have been the early Christian Era, then those Patrollers will try to find the behind-the-scenes events leading to that regime in order to prevent it, no matter how powerful the Exaltationists have made themselves later. However, the Exaltationists would control the entire subsequent history of their altered timeline and might even, as is suggested a couple of times, have organized their own Time Patrol to defend that timeline.

Does Manse Everard breach Time Patrol security when he leaves Bach's St Mark Passion, unknown to history but recorded by a time traveler in Leipzig Cathedral on Good Friday 1731, playing while he answers the phone in his New York apartment? No, because that is his unlisted phone number given to only a very few people and the caller is in fact Wanda Tamberly, Time Patrol recruit.