Hello
I saw many people (if not all) standing for berachos before megillah reading.
Mishna berura says to stand 690:1 and shaar hatziyun + machatzis hashekel to
what is the Rav position on this subject ?
I can’t tell you the Rabbi’s exact calculations but you can look at the Kaf Hachaim for opinions both ways.
On a practical note he has everyone in shul sit.
Similar to his psak that all sit by the entire Torah reading.
Does he give any reasons for siting
see his Teshuva in Ohr Yitzchak.
Vol 1. Ohr Hachaiym #53