There is actually a place named Londonderry just outside of Sussex. In researching the area I know that there were a number of Londonderry natives who migrated there. However, there are still a lot of families whose place of origin is simply Ireland. It may be that quite a few of these were Londonderry area.
I have in my quick access notes the following County Londonderry natives (born in the late 1700s or early 1800s) who settled in the vicinity of Sussex, New Brunswick, Canada (some a bit closer to Coles Island).
Joseph Leggett Mullin
Elizabeth relict of Robert Reed, of Newtown Limavady
Edward Hamilton of Newtown Limavady
Elizabeth Williams of Newtown Limavady
Matthew Ferguson, native of Newtown Limavady
George McAuley of Ballykelly
John Hunter native of Parish of Macosquin
James Lynch of Laremount
Elizabeth McAuley widow of William McAuley
John McCaw of Coleraine
William Macky of Coshquin in Liberties, Londonderry
Andrew, Thomas and David Phillips of Dungiven Parish
John Bond
John Calvin
George Cochran
Agnes Ann Cowan, widow of James Cowan
Eliza Crawford
Nancy Gurney
Mrs. Roseanna Hunter
Richard Hughes
Martha Hunter
Rachel Hunter
Samuel, James and William Irons
Robert Kee
Barnard Kelly
Joseph Kennedy and his wife Mary Christie
Margaret Kilfillen, widow of John Norry
David Kincaid
John Marshall
Thomas Mason
Mrs. Jane McEwen, widow of William McEwen
Andrew Mackie
James Mackie
Hugh McLaren
Ezekiel McLaughlin
Martha relict of William McLaughlin
John Parks
Alexander Quigley
Robert Ross
John Smith
William Smith (married Jane Murphy)
Robert Snell
Martha, wife of Adam Todd
Samuel Thompson
William Young