Is there any evidence that Vayetar Yitzchok, or Henau etc. had any siginifcant impact on the siddurim or the Nusach of Eidot Mizrach? I have been presuming that they did not, and therefore a good Eidot Mizrach siddur provides me with a reliable reality check. If my premise is faulty, please advise. Thank You. Shalom and Regards, RRW