Joan Merle McInnes - Re father of Francis Jane Davidson

N.Z. govt birth records state Francis Jane Davidson "A.K.A. Davison", and her father was Thomas Davison -- I discovered this when researching my husbands N.Z. genealogy. My husband is Lindsay Bill born in Whangarei, 1949, and grandson of Frances Jane Davison, as his mother was Frances May McInnes (sister to Joan McInnes) before marrying Albert Bill. I am, Kath Lindsay's wife, and have twin daughters, who would like to know more about their N.Z. ancestry. This info. may help in finding more about Thomas Davison ( not Davidson), inform me if this is incorrect !