I too have ancesters from Donegal Co Ireland. I'm hitting a stone wall on the name and when my ancesters came to America. I was told that Glackin, Glackens, & Glacken were probably all from the same branch but the spelling was changed in the records when they came to America. I'm starting to wonder if my branch was also originally a Glackin. If there is any information on this spelling change please let me know to I can search more affectively. Also, what about that original name in Donegal of O'Glasian. Was this was Glackin came from?