I am informed by Sport Ireland that Athletics Ireland is the National Governing Body for athletics in Ireland. Since 1924, Athletics Ireland has been affiliated to the International Association of Athletic Federations (IAAF), the world governing body for the sport.
Under IAAF statutes, Athletics Ireland's jurisdiction at international events covers the 26 counties of Ireland and, as such, the status of Ireland at European and World Athletic Championships is on that basis.
All National Governing Bodies of Sport are independent, autonomous bodies and are responsible for their own governance procedures and competition rules for their sports. I would suggest that the Deputy contact Athletics Ireland directly for any further information in relation to this matter. Contact details for Athletics Ireland at (01) 8869933 or email admin@athleticsireland.ie.