Joint ownership of rental property does not necessarly need to be on a 1065.  They can each report their share on their personal tax returns.

"A joint undertaking merely to share expenses is not a partnership. Mere co-ownership of property that is maintained and leased or rented is not a partnership. However, if the co-owners provide services to the tenants, a partnership exists."
https://www.irs.gov/instructions/i1065#idm140242305001840