Q. Regarding one that has yortzait on Purim and wants to make a siyum, Horav Shlomo Miller advised that if possible, in this leap year, he should make a siyum on both days of Purim, as one does with reciting kaddish (see question 999).
On a regular year he does the siyum during the Purim seuda. On this year on the first Purim since there is no seudas Purim, it would be difficult to do a special seuda for the siyum during the day or the afternoon, as it is a working day. Is it possible to arrange the siyum on the eve of Purim (leil Purim), when family and friends could be invited?
A siyum is a seudas mitzva. Does the (marbim beseudah) adding to a seuda that the Rema advises to do on Purim Rishon qualify as a seudas mitzva?
A. Horav Shlomo Miller’s Shlit’a opinion is that the seuda of the siyum should be done during the day, as the regular Purim seuda is done and on it more food should be added to comply with the opinion of the Rema. As far as getting family and guest to join, which may be difficult in the afternoon, one can start the seuda while it still day and have the rest of the guest join later.
Horav Shlomo Miller’s opinion is that even when there is no siyum, the adding to a regular meal during Purim is considered a seudas mitzva, since after all Purim Rishon also commemorates the nissim that occurred, and this constitutes a seudas hodo’a. (See Chassam Soffer O.H. 208).
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a