So she's a bit older, but unlike Jax she isn't able to skip the year she missed?  I never mentioned, should have but forgot, the school gives a test similar to the end of year exam to determine if students are ready for the next year in the event they miss one.  Jax passed the second year exam, and moved into third.  I guess Moirah failed hers and is still in first?  
Was she given her mother's last name instead of her father's?  

Is she related to any pureblood families we should know?  For instance, Me and Apoalo decided that Jax and Dana's mother was a Selwyn, and Aeden is their cousin.  

So... house... This is a hard one.  Hard work and perserverance are super Hufflepuff, but her flaky nature is also its antithesis.  The Sorting hat reads her mind, not her history, so it's possible that it'll put her in Slytherin as a pureblood, but she doesn't really have any traits for it.  
I think her strongest association might be Gryffindor.  For her passionate determination, and willingness to jump into action.  
I'm actually going to openly ask for outside opinions on this, because it's tricky.  

I wanna give her Cherry with Unicorn hair.