Scotland U21 boss Stark faces selection headache
Stark said: "It's just a factor of this job I have to deal with.
"Those three have been a massive part of this team and almost all our goals came from that department.
"Naisy is out injured, Fletch will probably remain with the full squad and Ross got a call-up by George for the game in Prague recently.
"So it's not out of the question that we won't have any of them.
"I'll speak to George about it before the Northern Ireland game. It's only a friendly but he's trying to finalise a squad for the World Cup qualifiers.
"His team is the most important. We have to help George as much as we can and he dictates in a situation like that.
"On the plus side it lets strikers like Graham Dorrans, Ross Campbell and Steven Lennon stake a claim."