I'm of the opinion that you can report your share on your respective Schedule E. Using a partnership is optional.
I'm in a similar situation, and we each report 50% on our Schedule E.
Some hastily obtained references:
https://pen.do/blog/filing-rental-income-property-tax/
https://ttlc.intuit.com/community/investments-and-rental-properties/discussion/my-father-and-i-co-ow...
https://pocketsense.com/taxes-joint-owners-rental-income-8555235.html
