fitting in a middle name

[thellamaqueen.livejournal.com]

My husband and I are adopting two children, and we have been talking a lot lately with them about names.  Legally, they are named Mastor Ishmael (5 years old) and Bryanna (3 years old, no middle name).  Mastor decided long ago that he does not like his name and wants to go by Matthew.  We have been calling him Matthew since the 3rd day he has lived with us.  Bryanna's name fits her, but I would like her to have a middle name, and I see this as my opportunity to have a little bit of say over my own child's name (yay!) I have spent years poring over what I would name my biological children if I ever had them, but now that I have a real, live 3-year-old in front of me with an established first name, I can't for the life of me settle on a middle name.  When the adoption is finalized, they will have our last name, so they will be:

Matthew Ishmael B----- (rhymes with beacon)
Bryanna _______ B-----

I am looking for suggestions for Bryanna's middle name.  I had always wanted my first daughter to have the middle name Betsy (it is a family name), but it just feels too cutesy and kind of weird with so many Bs.  I am leaning towards Alice right now, as Bryanna loves Alice in Wonderland (and so do I!), but I'm not sold on it the way it sounds.  I guess I am looking for something that sounds "right" between her first and last name, and something that fits in style with her brother's name. I am at a total loss!