That's what I meant exactly.
Say, your phone is A (priority #1), your wife's is B (priority #2).
When both A and B are present, the A is connected to. If A is not, then B is connected to (you can connect up to 7 phones, I believe). The BT tries to connect to them starting from priority 1 down to 7.
Therefore, if both A and B are present, and you want B to be connected, the only way is to turn off BT on the phone A so that CX9 will give up on it and try to connect to B.
This is what the manual implies. I only have 1 phone connected to my CX9. No way I can try it quickly. Maybe someone else can shed more lights on this.