Allow multiple individuals to reserve the same time slot

Hi, I have added the code snippet plugin and added the following code

function increase_capacity( $capacity, $service_id, $worker_id ) {
return 10;
}
add_filter( 'app_get_capacity', 'increase_capacity', 10, 3 );

I still cannot get the time slot to allow for more than one reservation. Can you help?

Thanks