I believe that I am descended from the Giffin that moved to Antrim in Ireland. The name has variously been spelt: Given, Givens, Giffen, Giffin.
My branch settled in Dunnygarron, just outside Cullybackey in Co. Antrim. I can let you know more if this is of interest.
I'd be interested in the source of the story about the three brothers from Ayrshire. There is some family history indicating that my Givens were descended from an Ayrshire family and inherited from the Laird of Drumochrin (many different spellings).