Q. If one is attending a bris milah that is going to be milchigs, may/ should one bring his own meat in order to fulfill his obligation according to all opinions (including Magen Avraham), or is this haughtiness? I feel very strongly that a bris milah should be fleshigs, but others for whatever reason do not conduct themselves this way.
A. See question (1591) above. Horav Shlomo Miller’s opinion is that it is the baalei simcha or the people who are making the bris and serving the meal who determine what the content of the banquet will be. Therefore guest, out of simple derech eretz and proper decorum, should avoid bringing their own food. In addition it should be avoided due to kashrus concerns, such as mixing meat and milk, or bringing food that others may consider of questionable kashrus standards, that would be detrimental to the baalei simcha and guest.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a