Answer:

SIB

Answer	Crossword Clue
SIB	Bro or sis
SIB	Bro, briefly
SIB	Bro, generically

SIB	Bro, e.g.
SIB	Twin, e.g.
SIB	Bro, perhaps
SIB	Bro, maybe
SIB	One of the kin
SIB	Member of the fam
SIB	Twin, perhaps
SIB	Brother or sister

SIB	Kinsman
SIB	Close kin
SIB	Sis or bro
SIB	Auntie, to Mom
SIB	Short relative?
SIB	Family member
SIB	Bro, for one
SIB	One of the fam

SIB	Sis, say
SIB	Luke, to Leia
SIB	Michael or Janet, to Tito or La Toya
SIB	Michael, to Janet or La Toya
SIB	Relative, briefly
SIB	Rival of a sort
SIB	Unc, to Pop
SIB	Lisa to Bart, or Bart to Lisa

SIB	Close relative, for short
SIB	Charlie, to Emilio, briefly
SIB	Close kin, for short
SIB	Likely bunk bed partner, briefly
SIB	Bro to sis
SIB	Close relation
SIB	Dakota, to Elle
SIB	Jacob, to Esau, for short

SIB	One of a quint's four
SIB	Meg, to Jo
SIB	Unc, to Dad
SIB	Sis, e.g.
SIB	Relative