I want to know if there is an issue with a guest at a Seder arriving with a non-Jewish spouse. The issue arises as my wife and I both come from non-observant families, but we have become relatively frum (like everyone, we still have a way to go but we try....). All the food etc will be done in my houseand the guests know better than to bring food as a gift or for use during the meal. Even knowing that, I still feel uncomfortable having a non-Jew participating in a pesach seder, esppecially as I try to find additional facts and commentaries to try and teach my children during the course of the meal. Which leads to my dilllema- the family expect to come to me for at least one night of the seder (we won;t go to them for obvious reasons), but it brings to the table the intermarried couple. So, how much of an issue is this halachicly, and if it is an issue is there anyway around it that would remain within the boundaries of halachah.
There is a halachic problem with having a non-Jew at a Yom Tov meal because of the concern that you might cook for him on Yom Tov. This concern,of course, is not applicable on shabbat when no cooking is done at all - for Jew or non-Jew alike. On Yom Tov, however, it is permissible for a Jew to cook for himself or other Jews but he is forbidden to cook for a non-Jew and therefore this concern arises. When necessary, for example when a potential convert is hosted at a yom tov meal so that he can learn the halachot, this problem is surmountable: no cooking is done at all for either the Jews or the non-Jews. Potential problems with non- Jews moving open wine bottles can be overcome by using only pasteurized wines. The main problem raised by your question is that of giving legitimacy to a relationship which is not only forbidden but threatens the survival of the Jewish People. The answer to this question, however, is an individual one. Is the non-Jewish spouse thinking of conversion? Will boycotting the family gathering weaken the continued Jewishness of the other family members or perhaps strengthen it when they realize how serious a prohibition intermarriage is? Will having this couple at your seder harm the education of your own children who may come to view this relationship as acceptable? Either weigh these considerations yourself or discuss them with a posek who can consider with you your specific situation.