Information on Thomas Shields

Im researching my paternal ancestors.My father was born Laurence Shields then adopted his step fathers name Sewell.His father was Laurence Thomas Shields born Wellington NZ26/12/1896.. To Thomas Shields born Scotland 25/12/1854?? Mother Helena Elizabeth Shields nee Sievers, Married 02/07/1887. Helena' parents Carl Augustus and Charlotte Sievers. Her siblings, William Louis, Rossetta, Mary Anne, Charlotte Clara, Emily Sarah and maybe Aileen.