Appointments more than one book for one time slot

Want to set a 10 capacity for one time slot. There is two possible solution.
a) using dummy service providers, but it goes to pain if you have 30 capacity.
b) using this code;
function increase_capacity( $capacity, $service_id ) {
return 10;
add_filter( 'app_get_capacity', 'increase_capacity', 10, 2 );

But I have two different service provider for 3 different services, so it causes conflicts. Do you have any other advice to solve it?