“Immediate family” of any natural person means any of the following (whether by the full or half blood or by adoption):
(a)
The person’s spouse, father, mother, children, brothers, sisters, and grandchildren.(b)
The father, mother, brothers, and sisters of the person’s spouse.(c)
The spouse of a child, brother, or sister of the person.
Source:
Section 5100.8, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=FIN§ionNum=5100.8..