Found Isabella on the 1871 census, but not John. Have you any more information about his family - father, mother, etc
Berwick, RG10/5182, Folio 16/Page 26
Row Green
Peter Buglass, Hd, 42, Fisherman, Berwick
Ellen, Wife, 43, , Scotland
Isabella Miller, Daur, 22, , Scotland
John, Son, 19, Fisherman, Berwick
Rachel, Daur, 17,, Berwick
Thos ?, Son, 15, Apprentice fitter
Jane, Daur, 7, Scholar
next door is
John Buglass, Hd, Wid, 78, Fisherman, Scotland
Hope that helps!