Peter and Hannah Fitzgerald, settled in Georgetown, in the South Island of New Zealand

I can't tell if you already have the birth info for Peter Fitzgerald or not. The article indicates that Mr. Gamble found the information.

The subscription site Roots Ireland has two baptismal records in Co. Kildare around 1832.

Peter Fitzgerald baptized July 2 1828 in Naas with father Richard Fitzgerald and mother Eliza Loughlin

Peter Fitzgerald baptized June 28 1835 in Clane father James Fitzgerald and mother Barbara Doyle

I was not able to locate a marriage to someone with the first name Hannah.

Roger McDonnell

Thanks you for your noble work!

Roger