Joining from the U.S.

My great-grandparents Richard Joyce, sonof Michael Joyce and Anna Welsh, and Ellen nee Joyce, daughter of Patrick Joyce and Margaret Baker, emigrated to Pittsburgh in the U.S. around 1880 or shortly thereafter. They were married in Pittsburgh in 1885. My hope is to learn more about their families of origin, and ideally to connect with cousins from the same heritage. Both were born in the early 1860s, seemingly before 1864, when civil records were mandated. To date, I have found nothing about them in the parish records at NLI. Based on my late grandmother's recitation of her aunts and uncles, I believe that I have found 3of Ellen's younger sisters' baptisms in the Derryinver townland (Renvyle/Rinvyle area): Honor in 1865 and twins Anne/Anna and Catherine in 1868. That's all I have to go on. Any ideas about how to pursue my research are most welcome.