You could still use Bree for a nn with the name being Aubrey- lots of nicknames aren't exactly like the fuller name.
Middle name suggestions
Olivia Brynn, Olivia Rae, Olivia Jane, Olivia June, Olivia Rose, Olivia Maureen
Aubrey Jane, Aubrey Belle, Aubrey Grace, Aubrey Nicole, Aubrey Lou, Aubrey Elaine, Aubrey Margaret
eta- scratch Nicole!