PMPro Sponsored Members Example Variable seat pricing

my_init_override_sponsored_members_pricing_update.php

<?php   // do not copy this line.
/**
 * Sponsored Members setup with child seat costs at checkout.
 *  SPONSOR SEAT + 4 seats @ 1120 each
 * 		 + 5 to 10 @ 275 each
 * 
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

global $pmprosm_sponsored_account_levels;	
$pmprosm_sponsored_account_levels = array(	
	4 => array( //Sponsor Level
		'main_level_id' => 4, // Sponsor Level AGAIN
		'sponsored_level_id' => 5, // Child Level
		'seat_cost' => 1120, // cost per seat 4 and under
		'min_seats' => 4,
		'max_seats' => 10,
		'seat_cost_text' => '<br />(1120 each) and then for child seats 5 to 10 @ 275',
	)
);

/**
 * Remove Sponsored Members Pricing update and use our own.
 */
function my_init_override_sponsored_members_pricing_update() {
	remove_filter( 'pmpro_checkout_level', 'pmprosm_pmpro_checkout_levels' );
	add_filter( 'pmpro_checkout_level', 'my_custom_pmpro_seat_pricing' );
}
add_action( 'init', 'my_init_override_sponsored_members_pricing_update' );

/**
 * My custom pricing.
 */
function my_custom_pmpro_seat_pricing( $level ) {	
	// Only concerned about level 1
	if ( $level->id != 4 ) { // Change to Your Sponsor Level ID 
		return $level;
	}
	
	// get seats from submit
	if ( isset( $_REQUEST['seats'] ) )
		$seats = intval($_REQUEST['seats']);
	else
		$seats = "";
	
	switch ( $seats ) {
		case $seats < 5:
			$level->initial_payment = $level->initial_payment + ($seats * 1120);
			$level->billing_amount = $level->billing_amount + ($seats * 1120);
			break;
		case $seats <= 11:
			$level->initial_payment = $level->initial_payment + ($seats * 275);
			$level->billing_amount = $level->billing_amount + ($seats * 275);
		    break;			
	}
		
	return $level;
}