656. Almost Forgetting a Yahrtzeit

90:22 If a non-Jew bought merchandise from a Jew and he comes to pick it up on Shabbos, the Jew should prevent this if possible.

90:23 If a person has yahrtzeit on Shabbos and forgot to light a candle, he may instruct a non-Jew to light one during twilight but not once Shabbos has begun.