The + and - button are not present as AF component and are part of layout so they are not configurable by default. You can customize accordion layout for which you add button in the layout and write click script for updating the drop-down. Alternatively you can use any other layout and drop buttons and add the script
this.panel.instanceManager.addInstance();
in the click expression for simulating + button and
this.panel.instanceManger.removeInstance()
to simulate - button.