Esau had 15 children as the son of Issac. He did not need any Zilpah or Bilhah. His wife was able to just have one baby after the other simultaneously after Esau went in onto her; copulated with her. Jacob may have been Abraham's.

Esau had 15 children as the son of Issac.  He did not need any Zilpah or Bilhah.  His wife was able to just have one baby after the other simultaneously after Esau went in onto her; copulated with her.   Jacob may have been Abraham's.