Surname Farady

I have a birth cert for my father William Farady born in the Rotunda Hospital 12.10.1912 his parents beeing William Farady and mother Margaret O'Sullivan. After that NIL!!! He was brought up by the Keegan Family in Finglas with the Name Thomas Keegan and he was in his late 20s early 30s before he discovered by accident that He was NOT a Keegan. The family refused to give him any more informaton. My last contact with the Keegan family was around 1971 when Uncle John Keegan and his wife visited me in London as they had been unable to attend my wedding to James MacKevoy, my first husband.
PLEASE can anyon help me find the Keegans from Finglas, I would simply like to be in touch and IF anyone has any ideas re the surname Farady i would be most greatful

thanks