Glenda's mother, Avis McCutcheon, had compiled a lot of material telling their family story. After she passed away the couple began adding to it.
"That's how it all started, with Avis," Mr Sheaffe said, "I've been the collector of material and writer, and Glenda's been there the whole time, we did everything together."
The books are the result of extensive travel - from Germany to Ireland - and gathering photos and letters from local residents who did not even know they were related to the couple.
Some descendants of the four migrant families - who settled from Napier to Norsewood - were still located in Hawke's Bay, and others are spread throughout New Zealand.
"It [took] years of us going and having cups of coffee with relatives that we didn't know, and Stephen writing masses about people," Mrs Sheaffe said.
The couple were delighted with the result of their effort - with the books revealing Hawke's Bay in the colonial period.
Through pictures, letters, and stories, the impact of the respective families in shaping the area - from their involvement with the early Napier harbour board, to opening Napier's first bike shop - is captured.
The books also reveal how the families became intertwined - through occupations, or religion - to reach Glenda and her five siblings.
Despite the different stories of the four families, they had one shared event - all relatives spoken to knew where their ancestors had been when the 1931 earthquake hit, which had killed a couple of Mrs Sheaffe's relatives.
Their tales were just some of those remembered in the glossy pages of the books. Others included the racism experienced by Mrs Sheaffe 's German ancestors in Napier during World War II, and the tragedy which befell descendants of the Fischer family, when four of their children died of diphtheria within two weeks.
Each book is dedicated to Mrs McCutcheon.
Mrs Sheaffe said, "it's just sad that she's not here to see it, because she would be so delighted."
With the completion of the books, Mr Sheaffe said the promise he made to his mother-in-law had been fulfilled.
Finishing them was a "wonderful relief in some ways because I've been doing the three [books] together."
Their three children now had their genealogy on hand, and although the couple's eight grandchildren were too young to be able to appreciate the books, Mr Sheaffe said they would when they were older.
The books did not contain any information about the current generation, as Mrs Sheaffe said "that's for somebody else to do."
As well as giving copies to family, the books have also been given to the MTG, and the Napier Library, and will be sent to the National Archives in Wellington.