Call 'em the Filipino "Partridge Family" ... because it seems ALL of the Pacquiao's are obsessed with singing -- and Wednesday, Manny's Aunt Lilia flexed her pipes with a street rendition of "Let It Go!"
This video is amazing ... Manny's extremely spirited auntie is PUMPED for the fight -- and told us why she's convinced her nephew's gonna beat Floyd's ass!
Then, after more Pacquiao family members gathered around Auntie Lilia ... they broke out in song!
Ya gotta watch this clip -- these guys are so much fun!!!