Multiple jQuery inputs or binds in Customizer Control Javascripts

I think the part you may be missing is that you don’t have to use the value that is passed to the function. You can still reference the setting inside the callback function, including other settings. So you can do this:

// Run a callback when both of the settings are registered.
wp.customize( 'yeah[part_one]', 'yeah[part_two]', ( part_one, part_two ) => {
    // Run callback when part one is changed.
    part_one.bind( () => {
        $( '#htmlcss > location > yes-in' ).css( { 'specificcode': part_one.get() } );
    } );

    // Run callback when part two is changed, but using the values of both part one and two.
    part_two.bind( () => {
        $( '#htmlcss > location > yes-ok' ).css( { 'specificcode': part_one.get() + part_two.get() } );
    } );
} );