Morris has been named in the Ireland U21 squad to face Montenegro on Tuesday, although illness is likely to force him out of the game at Terryland Park.
On-loan Chelsea midfielder Cork could also be in action on Tuesday night, as he is in the England U19 squad due to take on Russia at Milton Keynes.
And striker Jonathan Forte will be in Barbados to represent the Caribbean nation in a World Cup qualifier against Dominica.
United forward Martin Paterson was left out of Northern Ireland's squad to face Georgia on Wednesday night as he is in hospital with gastroenteritis - making him a doubt for Saturday's Championship trip to Leicester City.