Just gets more confusing as it goes. The family tree resembles the Gordian Knot. As things are I'll probably need graph paper or Vizio to chart this out.
Putting aside the insane family relationships, just why does she want to be a concubine? In a European setting the position doesn't exist (Thank you holy mother church and you don't even want to think about it under Talmudic law). Under Asian custom she is asking to be made a slave(concubine literally translates as female slave from the Chinese) with no rights and not even a family name anymore.
So at the very least there needs to be some exposition of what the marriage customs are in this world