Barretts in Cork

I am looking for info on a William Barrett from Cork --married to Margaret Lehane from Bandon. I do not know what part of Cork William was from. William's birth between 1821-1825. Margaret born between 1836-1840. I believe her parents were Denis Lahane and Mary Crean (or Keane or Crane) They had 11 children. Ancestry has some of them--but most I found through ship manifests coming to Boston in the 1880's--early 1900's. I have used the 1901 and 1911 Irish censuses and irishgenealogy.ie--but can find no info on William's exact birth place or parents. He was a widow in the 1901 census living with his son Thomas who was living in Inishannon--married to a Holland from there. Here are William and Margaret's children. Any help on William Barrett from Cork--1821-1825 would be most helpful. Thank you Sheila Barrett Gendreau

Margaret 1858

Mary 1859

Ellen 1861

John 1863 (my great grandfather)

Richard and his twin Denis 1865

Joanna 1866

William  1868

Thomas  1872

Catherine 1873

Elizabeth  1877