These siblings do NOT belong to James and Amelia Henderson.
This is an error perpetuated from incorrect acceptances of so called smart matching on MyHeritage with no checking as to the likely validity of the addition to the family of James and Amelia.
Please check the dates and places of the births for Frank / Reginald / Everard / Flora and compare them with the dates and places for the births of the actual family of James and Amelia, who didn't emigrate to NZ until 1874.