User blog comment:Master Sima Yi/Contradicting and confusing terms in the Encyclopedia/@comment-1888015-20111202140651/@comment-1153722-20111202143035

It's never confirmed there was just one Grand Master of the Templar Order at a time either. Al Mualim and Altaïr couldn't, in any possible way, have led the Assassins globally, because of the lack of means to have contact over such wide distances. And that is confirmed by Ubisoft.

And because of that lack of contact, I highly doubt there was a "top dog" of the Order either. Especially since Al Mualim and Altaïr are explicitly called Mentors in ACR.