Q. When one wishes to leave in the middle of davening to go to another shul when they need help with the minyan, what is the earliest one may leave? May one leave after completing the quiet SE, if necessary to arrive to the other shul on time.
A. On a similar question 2082 regarding if one can leave a minyan to go to another shul where they struggle to complete a minyan and one was asked to come and help. We mentioned that the Mishna Berura (55) rules not to leave shul until the end of davening, unless one heard all the Kaddeishim until Aleinu.
Horav Shlomo Miller’s Shlit’a opinion is similar and one is permitted to leave after Aleinu and all the Kadeishim until then were recited, to go and complete another minyan. The Rov added that it is sufficient if you tell even one person before you exit the reason why you are leaving early”
However, when needed for completing a minyan, the Rov’s opinion is that if a minyan remains in the shul he is leaving, he is allowed to go.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a