Manager Michael O'Neill is hoping to persuade others to follow Scotland-born James McPake's lead in declaring for Northern Ireland.
McPake, 27, qualifies for Northern Ireland via a Coleraine-born grandfather and has opted to transfer his allegiance after failing to earn a Scotland call-up. He is one of four uncapped players in a 24-man squad for the June 2 friendly against Holland in Amsterdam, joining Swansea striker Rory Donnelly, Walsall forward Will Grigg and Burnley full-back Daniel Lafferty.
O'Neill said: "I spend a lot of time researching the available players because we need as many as possible. I have spoken to a number of others and some haven't made that decision at this point in time or aren't willing to change their allegiance at the moment. But we will continue to monitor and strengthen."
On the move to draft in McPake, O'Neill added: "James has a lot of attributes that can be very useful for us. He's versatile, can play anywhere across the back and he's been on the fringes of the Scottish squad. His agent notified me of his eligibility and we followed it up quickly, so this has all happened in the last couple of weeks."
The new quartet's presence, as well as that of recalled duo Jeff Hughes and Rory McArdle, is down to a host of senior players missing for the fixture - including Steve Davis, Jonny Evans, Gareth McAuley, Chris Brunt, Aaron Hughes and Dean Shiels.
O'Neill lost his first match in charge of the national side - 3-0 at home to Norway - and knows he faces an even tougher first away trip against a side who will be among the favourites for Euro 2012.
But with so many of his first-choice players out injured or otherwise unavailable, O'Neill is hoping there is plenty he can learn from the experience - not least how his fringe players react to the big stage.
"Injuries have played a big part in terms of the ones who aren't available," O'Neill said.
"It would be nice to have everyone available now but what is really important for me is that they are at the start of the World Cup qualifying campaign. But there are a number of others players in the squad who won't have had the opportunity to play at this level, against a team like Holland, before.
"It's important for me to see how they handle that because we will have games like this in the World Cup campaign - away to Russia, away to Israel, away to Portugal."