Rebuilds key values for array $pmpro_pages if empty in a multisite network.

pmpro-multisite-membership-pmpro-pages.php

<?php

/**
 * pmpro_multisite_membership_pmpro_pages
 *
 * Rebuilds key values if empty in a multisite network
 *
 * @requires Multisite Membership Add On [pmpro-network-subsites]
 *
 * @return array global $pmpro_pages
 */
function pmpro_multisite_membership_pmpro_pages() {
	if ( ! function_exists( 'pmpro_multisite_membership_init' ) || ! is_multisite() ) {
		return;
	}
	global $pmpro_pages;

	$primary_network_site = get_current_site();

	foreach ( $pmpro_pages as $pmpro_page => $pmpro_page_id ) {
		if ( ! $pmpro_page_id || empty( $pmpro_page_id ) ) {
			$pmpro_pages[ $pmpro_page ] = get_blog_option( $primary_network_site->blog_id, 'pmpro_' . $pmpro_page . '_page_id' );
		}
	}
}
add_action( 'init', 'pmpro_multisite_membership_pmpro_pages' );