Three Town players joined up with international squads ahead of matches in midweek. However, keeper Lewis Price has already dropped out of the Wales squad due to injury.
Price reported to Wales' Vale of Glamorgan Hotel ahead of Tuesday's friendly in Northern Ireland but after a medical examination was sent back to Town due to a thigh strain. Reports in Friday indicated that the Welsh were expecting Price to drop out and called up Burnley keeper Danny Coyne as cover.
The Town keeper was expected to win his fourth full cap in Belfast. Boss Jim Magilton is a studio guest on BBC1 NI's coverage of the game (Sky channel 973, 7.30pm).
Meanwhile, Price has revealed he has been talking to John Toshack about Real Madrid keeper Iker Casillas, who the Wales manager worked with when he was in Spain and is a player the Town glovesman greatly respects: "I've spoken to the gaffer about Iker and he knows that I am a great admirer of his style and poise.
"I feel he is a good all-round goalkeeper who has achieved so much in his career, despite only being a little older than me.
"He has certainly never looked out of place in the Real Madrid side, despite costing the club nothing. Madrid are full of superstars like David Beckham and Raul, but Iker has matched them all.
"I watch and monitor him every chance I get. I always watch Spanish soccer and like to analyse Casillas's performances - he is very much my hero."
Casement is in action on Tuesday afternoon for the Northern Irish U21s with their game against Wales at The Oval in Belfast kicking off at 3pm. If he plays, the defender will win his first cap at U21 level.
Haynes and the England U19s take on Poland at Bournemouth's Dean Court on Tuesday (KO 7.45pm). If involved, the Town striker will win his first international cap at any level.
Academy central defender Tommy Smith will be away with the England U17s during the following week at a tournament in the Algarve.