Margaret Brennan b: abt 1868

Hullo all, 

I would apreciate any help in finding the birth record of Maggie Brennan, born abt 1868, probably in Kilkenny, and the marriage of her parents Michael Brennan and Ann Pinder (probably Pender) in about 1868. This information comes from the original copy of her marriage record in 1894 to William A Sabine in New York. The record states that this is her first marriage, so her maiden name must be Brennan. (In every record, she is Maggie, not Margaret)

I would also like to find her migration record. In the 1910 census she says she migrated in 1882. 

To complicate matters, two Noonan brothers, John and Michael Noonan, who also migrated to the USA, claim her as a sister. She is mentioned as 'Mrs William Sabine' in the obituaries of both men.

The parents of her brothers, Michael (b:1858 Muckalee Kilkenny)  and John Noonan (b: 1854 Muckalee) are Michael Noonan (b: abt 1815) and Ann Pender.(b: abt 1825). They married in 1839 at Muckalee and brought their children up there.

I am assuming that Michael Noonan Snr. died and that his wife Ann Pender then married Michael Brennan, around 1868 when Maggie was born, but I cannot find the record of Michael Noonan snr's death, his widow Ann's marriage or the birth of her daughter Maggie..

Any help appreciated!