Rubuta ci gaba don wannan sakin layi - Morrissey ya wakilci Kanada a wasannin kasa da kasa da dama, ciki har da IIHF World U18 Championships, da Ivan Hlinka Memorial Tournament da IIHF World U20 Championships. Morrissey ya taimaka wajen taimakawa kungiyar 'yan kasa da shekaru 18 ta lashe zinare a gasar zakarun duniya ta 2013 ta IIHF
, kazalika da tawagar 'yan kasa da shekaru 20 a gasar cin kofin duniya ta hockey ta duniya a shekarar 2015. An kira shi zuwa 2015 World Junior All-Star First Team, yana gamawa da maki hudu da darajar +9 da-kasa.