cosignatory
From Longman Dictionary of Contemporary EnglishRelated topics: Lawcosignatoryco‧sig‧na‧to‧ry /ˌkəʊˈsɪɡnətəri $ ˌkoʊˈsɪɡnətɔːri/ noun (plural cosignatories) [countable] SCLone of a group of people who sign a legal document for their department, organization, country etc Both cosignatories must sign the cheque.Examples from the Corpuscosignatory• We will need both cosignatories to sign the check.