Greetings, I thought I had read a final resolution of the Alter History/Brotherhood Schism question, that being that AH had an ongoing effect, & could therefore be ended by BS. Unfortunately my search skills are failing me, so I'm asking if the answer could be reiterated here.
Alter History ongoing effect ruling
A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
The internet black hole devoured the original answer
I confirm you that Brotherhood Schism will end the effects of Alter History.
See here A delayed effect that has been activated but not yet applied is an ongoing effect, and can still be prevented by something that prevents effects in general, such as "effects of that action do not happen." However, something that prevents a specific type of effect, such as bowing, will only negate a delayed effect when it is actually applied. [CHANGED Jan 6 2013]