The button between the window switches only locks out the rear windows, not the doors. I don't know of any rear door child locks, but the rear doors do not open when they are locked. The lock knob needs to be pulled up to open them from the inside, or the central locking needs to unlock them. You could change the lock knob to one the is shorter and therefore out of reach making it difficult to pull the knob up. The doors will still unlock with the central locking when needed.

Scott P.