http://revach.net/article.php?id=4979

Section: Halacha   Category: Tshuvos
Pri Megadim & Minchas Yitzchok - Does Anyone Party On Shusham Purim Katan?

The Rema says (OC 697:1) that although we are not noheg to be Marbeh in Mishteh and Simcha on the 14th of Adar Rishon, still we should be marbeh seudah a little bit in accordance with the machmirim who hold that Putim Katan is a day of Mishteh V'Simcha.

The Mishna Brura brings from the Pri Megadim that although we don't say tachanum on Shushan Purim Katan, the din of extra seudah is only on the 14th, even for those places that keep Shushan Purim like Yerushalayim. His Mekor is the Hagaos Maimoni brought by the Bais Yosef.

The Minchas Yitzchok (10:58) argues and holds that a closer reading of the Mekor will show that he was only talking about cities that normally keep the 14th. Even though they also have simcha on the 15th of Adar Sheini, in Adar 1 they do not. However Krachim that their main day of Purim is on the 15th should be marbeh in seudah on the 15th of Adar 1 as well.

Important Note: We bring this tshuvah as a starting point for discussion and not to convey any halacha. We try to convey the Tshuva to the best of our ability. We admit that our understanding may not be accurate. One should learn the tshuva to verify the accuracy of our interpretation. Please understand that this Tshuva may not be the final word on this topic. One should consult a Rav before drawing any conclusions.