Patrick Langan/Mary Sweeney /ames Langan/Letterkenny

Searching for information on my Great-Great-Grandfather Patrick Langan. Letterkenny, Donegal. Around 1830-76.
I just spent a month in Scotland tracing further family information and I now have a more accurate description of what his information is. LDS familysearch site has Patrick Langan and Mary Sweeney as parents to James Langan, born Jan.9 1876, Letterkenny Donegal, my Great-Grandfather. On James Sweeney aka Langan’s death certificate it shows Patrick Langan and Mary Sweeney as parents and under his name in brackets is the note (formerly Langan) until I had a copy of that I had no idea what the names of his parents were. Or that his birth had originally been registered in the Langan name. His eldest daughter Annie Sweeney witnessed the certificate.I assume she had this information from him during his lifetime. It wasn't until I got back to canada and reread some of my earlier correspondence that I was able to make the connection without it just beinga good guess.James’ Mary Sweeney was sent to Australia after James' birth. James was left with his grandparents Hugh and Mary Sweeney of Letterkenny.
Kind Regards

marilyn anne love

Calgary, Alberta, Canada
researching:
Sweeney/Langan
Coll/Fearns/Ferrands
Connor/McBride/Smith
Boyce/Buchanan/Burke/Butler
Donegal/Scotland/Australia