Bilhah
From Zissil
Bilhah was the third of Yackov's four wives and the mother of Dan and Naftali. She was a half sister of Rachel and Leah from their father Laven though his marriage to a concubine.
Maidservant
Despite being older then Zilpah, Billah was given as a maidservent to Rachel when she married Yackov since the younger Zilpah was already given to Leah in attempt to fool Yackov that she was really Rachel, the younger of the two.