I say, and with God's success: The expiation for an oath is paid to ten needy people. If he wants to give it to his sister who has children, for example, ten in number, each one of them counts as a needy person. If they do not reach ten, it can be paid repeatedly on another day; because the need for the needy person renews every day, so on the second day, he is considered as another needy person. And God knows best.