First given name from birth of child found from birth search on New Zealand BDM website in January 2021:
1921/14196. Grylls, [No record]. Mother: Martha. Father: Edwin Charles

Maiden name, year and country of marriage from search on New Zealand BDM website in February 2021:
1902/3818. Bride: Martha Cribb. Groom: Edwin Charles Grylls

Full date of marriage of 15 July 1902 from further searching in February 2021 on BDM Search by incrementally changing the date range for the marriage.

Year and place of birth, date and place of death, name of mother, from findagrave.com found in March 2021:
Name: Martha Grylls
Birth Date: 1881
Birth Place: Waikato, New Zealand
Death Date: 1 May 1936
Death Place: Thames, Thames-Coromandel District, Waikato, New Zealand
Cemetery: Manunui Cemetery
Burial or Cremation Place: Manunui, Ruapehu District, Manawatu-Wanganui, New Zealand
Mother: Diana Mcgiven Cribb
Spouse: Edwin Charles Grylls
Children: John Richard Grylls
URL: https://www.findagrave.com/memorial/88477321/martha-grylls