Your family members
If you’re a British national (overseas), your family members can apply as your ‘dependant’ if they normally live with you.
A dependant can include your:
husband, wife, civil partner or unmarried partner
child or grandchild under 18
child 18 or older, born on or after 1 July 1997 (and their partner or child under 18)
parent, grandparent, brother, sister, son or daughter (18 or older) if they live with you and are very dependent on you for their care
https://www.gov.uk/british-national-overseas-bno-visa/your-family-members