@Frank1622 Since listings can't be transferred between primary hosts, you have two choices:
a) Help your father-in-law set up his own account and create a new listing with himself as the primary host. The follow these instructions to add you as co-hosts: https://www.airbnb.com/help/article/1244/adding-cohosts-to-your-listing
b) If you have the full consent of your father-in-law to leave you in full control of the listing and payments, you and your husband can remain the primary hosts of the property (Airbnb does not require that the hosts be the actual homeowners). I'd recommend making it legal with a contract designating you as the property managers in his employ, both for tax purposes and for your protection in any disputes that might arise with family members.