Manse is captured in 1926, timeline 2, whereas Wanda has fled through time and space to 180 AD, pre-divergence. She thinks:
"Other agents would be heading futureward 'now', for a value of 'now' that only the Temporal language could express, across the wave-front of actuating upheaval. They'd see the altered future; some of them would flit straight back downtime. They'd gather, assess the situation, and then they'd act."
-SM Stirling, "A Slip In Time" IN Greg Bear and Gardner Dozois, Multiverse: Exploring Poul Anderson's Worlds (New York, 2014), pp. 63-91 AT p. 73.
I disagree. Most, possibly all, time travelers, including Time Patrollers, who traveled from the post-1914 timeline 1 into pre-1914 eras returned futureward into timeline 1. Wanda herself has done this several times, as has Manse etc. Two possibilities:
if no one has traveled futureward into timeline 2, then Wanda and Manse are alone in knowing about that altered timeline - apart from the time criminal who caused it, of course;
if say one or two Time Patrol agents have traveled into timeline 2, then they should act as Wanda thinks they will and enlist help from some other agents in the past while trying not to disrupt the course of events too much in the process.
There is one other factor here. If, e.g., one Patrol agent traveled futureward into timeline 2, then s/he did not return as planned to timeline 1 so some colleagues should have investigated and might have identified the problem?
However, no agents setting out to travel pastwards along timeline 1 from a post-1914 date to an earlier post-1914 should have arrived in timeline 2.