Sadly very little is straightforward in my backward little part of the country. There are certain popular songs that will forever be associated with one side of the community or the other. The troubles may be over, but the hatred will be here for many generations to come. Most venues I play in do not allow The Best - Tina Turner, Daydream Believer - Monkees/Neil Diamond, or Country Roads - John Denver/Hermes House Band to be played as they may cause trouble/offence, due to the reactions of a bunch of small-minded bigots. I sincerely doubt that the guests at your function would mind at all, but it's worth being aware.
I've never seen The Gambler - Kenny Rogers or Sweet Caroline - Neil Diamond get anything but a good reaction at any venue in this country, either as a DJ or a guest. They seem to be unoffical Northern Ireland anthems. There is also a big country following in most of the province, so a bit of Garth Brooks may work well. But in all fairness, the playlists I rattle out vary little from what the rest of you play. A good party tune is a good party tune (although even the phrase "party tune" has a double meaning over here

). But even just looking at some of the discussions on here will show you that I get the same reactions to the same songs here that Robster gets in Lancashire, and Vokf gets darn sarf. Heck, they even seem similar in East Anglia!!!
If you were wanting to pay a friendly nod to the visitors then there are plenty of suitable songs that work with all crowds. Tell Me Ma has been mentioned, others worth considering are Teenage Kicks - Undertones, Brown Eyed Girl - Van Morrison, or anything by
Scum Snow Patrol

, all successful artists from Northern Ireland. Don't play something silly like Belfast Child though, please. Really, theres nothing to worry about. We're a strange little country, but we know how to enjoy ourselves, and I'm sure they'll enjoy whatever you play. Have a good one!!!
(Oh and if you can get your hands on a novelty song called Horse It Into Ya Cynthia by a comedian called Conal Gallen, that could get a huge reaction from them!!!)