(i think but am no expert yet).
if Martial Arts adept(-s) go(-es) to different School than before, he or she should respect new Ceremony, exact execution of exercises which might differ from exercises trained before.
it's not easy to switch immediately for nervomuscular system is trained and new behaviors need to be re-trained, but effort should be made - i think at ease, Mindfully, taking enough of time (but not too much of time), to not create unneccessary dramas.
it's polite to be honest & true after all, this includes being true to Your training, behaviors & reflexes.
but old School's Teachers should not be abadonned, i also think. in my case, goal is to join Schools, not to create unneccessary schism.