Question:
Is a sibling dies erev Rosh Hashana , does one do the shul on Rosh Hashana?
Answer:
Assuming that the burial was done before Rosh Hashana, if the mourners sat, even a little bit before Rosh Hashana, Rosh Hashana finishes the shiva, and there is no issue with going to shul. Even if the burial was not before Rosh Hashana, being that we don't bury the deceased on Yom Tov or Yom Tov sheini, the brother may go to shul.
May Hashem comfort you
תכלה שנה וקללותיה
Sources:
O:CH 548-14, Igros Moshe O:CH 3 -76,161.
