cosignatory
co-signatory, n ~ (of/to sth) person, state, etc signing jointly with others 連署者(人、 國家等)
The US and the former Soviet Union were co-signatories of/to the treaty. 美國和前蘇聯(lián)都是條約的簽署國.
??? 情景例句
One tiny little touchdown, with just three minutes to play.