Bipolar Disorder in Family History - MOVED

Our 23 month old fd was abandoned 4 days after birth so we have almost no family history on either bparent. The bmother did let the CPS worker know she had been treated for bipolar disorder prior to her pregancy. We have no other medical history on any other family member but we do know there was a 10 year drug history with her fmother. How concerned should we be that the bipolar disorder may be passed on to our fd? She so far has exhibited night terrors or awakening periods in the middle of the night. Sometimes we'll think she's fallen back to sleep and then her eyes will slam open and scare the heck out of us. She doesn't look like she's looking at us, but through us. She can be the happiest girl most of the time but out of nowhere will hit me so hard in the face for no reason. She has head butted me several times, once so severely I thought my nose had broken. She will act agressively towards another person (adult or child) in one instance and then ever so sweetly kiss them and bat her eyes at them the next instance. Is this normal toddler behavior? Or should we be concerned? We are preparing to complete our adoption subsidy papers. We don't know if we should bring these issues up or not. We don't know if she'll need any care relating to this as she grows older. What would any of you do?