@Laurie155. First of all, the guest who is making the reservation should also be a guest staying at your listing. Airbnb requires this. You should ask the guest to cancel and ask the father in law to book directly. The son in law can even refer his father in law and both will receive travel credits. This way the receipt will be in the father in law's name.
But, to address the receipt issue, the guest can add his father in law's name to the receipt, but cannot remove his own as he was the one who booked.
Here are some helpful links:
https://www.airbnb.com/help/article/427/can-i-book-on-behalf-of-a-friend-or-family-member
https://www.airbnb.com/help/article/449/how-can-i-add-a-guest-or-business-address-to-my-receipt