While the primary halacha of refraining from eating a substantial amount before a holy day relates to the day before Pesach,[2] it is proper to refrain from even a moderate meal during the last quarter of the day on Friday.[3] In general, it is prohibited to partake in an especially big meal anytime on Friday day, but there is an exception for seudot mitzva[4] that fall specifically on this day,[5] and the Purim seuda is one such seudat mitzva.[6]
At first glance, since the Purim seuda does not apply halachically to your visiting family, whose Purim was the day before,[7] they do not have an excuse to eat at a time it is normally forbidden to do so. However, we can argue cogently to the contrary. One who makes a brit or pidyon haben on Friday makes an accompanying seuda,[8] and we do not find limitations on whom he may invite,[9] even though there are only a few principals of the simcha who are obligated in the seudat mitzva. It follows that the non-principals are permitted to join because these people contribute to the occasion’s festiveness, and they therefore enjoy the leniency of eating a seudat mitzva on Erev Shabbat. This would seem to apply as well to non-Jerusalemites participating in Shushan Purim and enhancing it, as important sources[10] write that Purim is properly celebrated in the context of a broad gathering of family and friends.
We would not say, however, that this is proof that your out-of-town guests have no more restrictions than you have. Consider that the nature of a seudat brit is such that in order to achieve even the basic festive setting (which traditionally includes at least a minyan of participants[11]), the ba’alei simcha by necessity rely on guests who are not themselves the ba’alei simcha. In contrast, in your case, it is plausible that since one’s entire community is celebrating Shushan Purim, participation is a mitzva only for those who are obligated in Shushan Purim and not for members of communities who celebrate at a different time. On the other hand, some festivity is appropriate for all Jews on both Adar 14 and Adar 15,[12] so that logically the guests are not really out of place.
It is even likely that the “prohibition” against eating a big meal in the morning is not a problem at all for your guests. The source to refrain from such a meal is a gemara[13] that relates how a family that set a meal on “Erev Shabbat” was punished. Although Rashi[14] explains that their main Shabbat meal was on Friday night, most interpret the gemara as referring to a seuda on Friday day. However, some maintain that such behavior is problematic only for those who practice it on a regular basis.[15] Some[16] explain that the concern is that a meal on Friday will detract from Shabbat preparations, in which case the problem is for the organizers, not for the guests. In your case, the organizers of the seuda and Shabbat meals are Shushan Purim celebrants, who must have the festive Purim meal that day. Only according to one interpretation of the gemara (albeit the one accepted by the Shulchan Aruch[17]) – that any occurrence of a big meal, even in the morning, can ruin one’s appetite for Shabbat food – should it be a real issue for guests and require a special mitzva-related exception.
In the final analysis, based on multiple possible grounds for leniency, we posit that it is appropriate to include your children in the seuda. The question remains whether any special limitations or recommendations are appropriate for this scenario.
Most years, we prefer to hold the Purim seuda in the afternoon,[18] but on Friday, it is preferable to start it in the morning[19] so that one will have enough time to recover his appetite by Shabbat.[20] (There is a serious albeit minority approach that maintains that one should hold the seuda at the end of the day and have it turn into a Shabbat meal.[21]) The involvement of out-of-town guests is an added reason to prefer an earlier meal, as for them, serious eating close to Shabbat is clearly problematic, and the advantages of enhancement of Purim by eating later do not apply directly to them. Therefore, starting the meal in the morning[22] is significantly preferable for the guests.
If the guests want to be stringent, there is logic for them to eat less than they otherwise might have if it were not Friday. In addition, it is not justified for them to get drunk or even drink a lot of wine, which would likely detract from a proper start to their Shabbat. (Even when Purim does not fall on Friday, it is difficult to justify one getting drunk when it is not Purim for him, in addition to the fact that we never favor drunkenness on Purim.[23])