Offhand, it's hard to say.
At the moment there's a lot of things up in the air. The Northern Ireland assembly is in suspension because the DUP and SInn Fein can't reach a power-sharing agreement. Having one party having the potential to heavily influence the administration could have a lot of awkward fallout. Sinn Fein while technically having seats in Westminster have always followed a policy of absenteeism because they're big on Northern Ireland re-joining the rest of Ireland, regardless of what people said in the referendums. If the DUP does head into coalition with the Tories, Sinn Fein might feel they would need to actually use their seats properly rather than have them as a PR element.
The Good Friday agreements were meant in some way to balance out the unionists with the nationalists, and then have a sort of limited oversight via a supposedly non-partisan British administration. But there was also a lot of vague wording in the agreement, it was originally meant to have a certain ambiguity to help bring all the varying groups together rather than try to jam specific hard lines down everyones throats, but I suppose that could be used to bend and twist it in all sorts of fun ways.