Is the money paid to register a father for Hajj—who died before performing it—considered part of the inheritance, or must it be returned to the one who paid it?

If the money was given to the father for Hajj, there is a detailed explanation:

1. If it was a gift and the money was received, or it was given to the Hajj agency and the father was informed, then the money becomes part of his estate and is distributed among his heirs, because a gift is owned upon receipt. If the recipient of the gift dies before the gift is executed, the money transfers to his heirs as absolute ownership without any condition. 2. If it was a loan, or with the intention of being returned and claimed, then the money belongs to the father and is a debt upon him, and it is taken from the estate before its division, because debt takes precedence over the division of the estate.