Complex sentence: Murphy himself looked into whether he could play for the Republic of Ireland, but it transpired that he was also ineligible for them because his closest relation, a great-grandparent, was one generation too far back to confer qualification.
Split into simpler sentences: Murphy himself looked into whether he could play for the Republic of Ireland, but it transpired that he was also ineligible for that country. Murphy's closest Irish relation, a great-grandparent, was one generation too far back to confer qualification.