After an emotional performance on Saturday evening, the British and Irish Lions flanker posted a tribute the following afternoon on social media.
“This week I suddenly lost my cousin and best friend Harri,” wrote Morgan under a picture of the pair at Principality Stadium in Cardiff. “He meant the world to us as a family.
“He loved so much about life, but his greatest joy was playing rugby for Brynamman.
“Yesterday I played my game in honour and memory of Harri. It felt important to go out there and make him proud, playing the game that he loved.”
Brynamman said that the loss of their vice-captain left “a hole that will never truly be filled”.
“A true warrior, immensely talented, and fiercely dedicated, Harri gave everything to the game, to his team-mates and to this club,” said a club statement.