Bernie,
You have a Bose system, I thought you could hear those speakers equally across a room. If you were to place the speaker closer to her and I am sure you will be able to hear it also.
Unless you need to keep the volume at a low level and the piano is over shadowing the speakers. Why not two 8” or 10” self powered speakers placed behind both of you -- controlling the balance with your mixer.
I always try to think less stuff. That also relates to fewer problems also.
John C.