Andrea

Nava was born to a distant relative of Mei. She is younger by 5 years or so.

She was given away to adoption a week after her birth, as her mother didn't want to deal with a child that would panda up. She was outcast and shamed by her family, and none of them speak to her anymore. 

They do not know what orphanage Nava was sent to, so they couldnt regain custody for her. 

Nava has a younger brother. Nava doesn't know anything about her heritage, and was somewhat normal, if not a bit shy, until she was about 16. (Her big emotional break was when she found out her mother gave her away because she was a girl, which broke her heart and devastated her.)

Her foster mother (who loves Nava dearly and has taken care of her since she was 3), or the orphanage employees have no knowledge of her heritage at all.