The only programmes that I have from the Northern Ireland Cup International Youth Football Tournament are seasons 1983 (1st season), 1984, 1985, 1986 (renamed the Northern Ireland Milk Cup) and 1988.
Motherwell Squad listed in 1983 as;
Gordon Henderson, Paul Smith, Gary Harrison, Derek Halliday, James McLean, Derek Walsh, Robert Kennedy, Stephen Aitken, Paul Tracey, James O'Hare, Stephen Connors, Martin McBride, Kevin McKeown, Mark Reilly, Ronald Findlay and Cameron Young.
They beat Coleraine in the final, were awarded the Tyrone Crystal Award given to the most successful team from outside Northern Ireland and the Player of The Tournament was Stephen Connors,
1988 under 16 Squad;
David Wright, Steven Nugent, Colin Nisbet, Andrew McVicar, Allan Brand, Philip Campbell, David Edgar, Paul Burke, Philip O'Donnell, Kieran Brady, Mark Dickson, Gerard Mitchell, Colin Wilkie and Chris Lambe. Team Official, Bobby Jenks.
1988 under 14 Squad;
Stuart McIntosh, David Arbuckle, James Fullerton, Andrew Wright, John Lavery, Anthony Smith, Nicholas McDonald, Marvin Wilson, Ryan Gallagher, Alex Burns, Brian McLaughlin, Steven Smillie, James O'Neil, David Patterson, Mark Dunn and Robert Bellingham. Team Official, Bobby Jenks.
Sorry no info on the Manchester United squad.
Hope all the above is of interest.