Purchasing a rental Property with my Father

I am closing on a triplex property tomorrow.  The property is in my Wife and I's name.  We secured it using our income/credit.  My Father however is putting up a significant down-payment.

He is getting the rent off of one of the units. Basically he will own 1/3 of the property.

How can we will not be on the deed or mortgage at closing.  How does he secure his interest in the property? I was thinking doing a $1 Lien? So we couldn't transact on it without his payout.

Any other ideas?