open the customn page in the child directory

change the line
$avia_config['currently_viewing'] = 'page';

into for example
$avia_config['currently_viewing'] = 'staff';

create a widget called staff

copy sidebar.php into the child directory

add before general shop sidebars

// staff pages sidebars
            if ($avia_config['currently_viewing'] == 'staff' && dynamic_sidebar('Staff') ) : $default_sidebar = false; endif;
            

and yes it is working!

do you need more info?