Changes needed in current app

I need a quote for a change to an existing Android child abandonment app. The operating logic is very simple, a QR code is applied to the child's seat, (therefore if present, the child covers the QR code with his back) and the phone will have the rear camera pointed at the seat, and the charger connected to the cigarette lighter socket. When the car is turned on, the device activates as it receives power from the charger and emits a sound to make it clear that it is operational as soon as the car is turned off and therefore the smartphone no longer receives power, if in the second preceding the switching off of the auto has detected the qrcode then emits a sound, in case it does not detect it, as the qrcode is covered by the child it goes into alarm. The change to be made would be as follows: if the phone is connected with the car's bluetooth handsfree, the smartphone does not emit sounds, but only from the car speakers. We need instead that the sound is also emitted from the speaker of the smartphone. I noticed that this thing then the double sounds the smartphone makes them when it receives a call. Do you think you can help us? To carry out a test you can also use bluetooth speakers or bluetooth headsets [login to view URL] - Here is the app