I have been invited to attend a Bar-Mitzvah party in which the preperations, including numerous violations of Shabbat, will be made on Shabbat, and the party will begin on Shabbat. (1) Would it be acceptable to go to the party after Shabbat? And, if so...... (2) May I eat food that was not cooked on Shabbat but was transported to the banquet facility on Shabbat? (I have been assured by the non-observant parents of the Bar-Mitzvah that the food will be ’Kosher’, although I assume that any food cooked on Shabbat must be avoided.)
Attend after Shabbat, say Mazal Tov, wish the young man that he grow to be a loyal member of the Jewish people- have a soft drink or L'chayyim on whiskey, but don't eat there. Aside from any other consideration you cannot assume that the food is kosher- who is supervising?