[Sono paatiewa [Hanakoga ________ ittadarooka] [Jiroga ________ ittadarooka]] (watashiniwa wakaranai).
the party-to-TOP Hanako-NOM  went-may.well.be-KA Jiro-NOM  went-may.well.be-KA I-DAT-TOP know-NEG
I don’t know which is true: Hanako may well have gone to the party or Jiro may well have gone to the party.