Immediate family includes:
Spouse
Domestic partner
Child
Parent
Sister
Brother
Stepparent
Stepchild
Grandparent
Grandchild
Aunt
Uncle
Niece
Nephew
Stepbrother
Mother-in-law
Father-in-law
Son-in-law
Daughter-in-law
Brother-in-law
Sister-in-law
Stepsister
I found this on the
Bereavement travel page, and I imagine they would consider all of those as so for SC entry.