Dragonair is a oneWorld airline. It is a CX subsidiary, thus not listed separately. See: https://www.oneworld.com/member-airlines/cathay-pacific (scroll down to the bottom).

Their lounge is fairly mediocre (at least for HKG standards) - use QF lounge instead (the same level, different entrance). Explain the situation and log to your account on smartphone and show them the status - should work...