Question:
If one has a child who is unfortunately intermarried, must they avoid the cooking of this child's non-Jewish spouse (assuming all other Kashrus issues are accounted for)?
Answer:
It is a very unfortunate situation, but they definitely have be careful about it. In fact one of the reasons for the prohibition is in order to avoid intermarriage. If the fire was turned on by the Jew, it would exempt the food from being bishul akum, (for Ashkenazim).
