This recipe will show the Group Leaders Expiration Date for the child's membership level.

pmpro-groupleader-child-expiration.php

<?php
/*
 * Show the Group Leaders expiration for the child in various places on frontend and admin pages in PMPro.
 *
 * 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/ 
 */

function my_pmprogroupacct_membership_expiration_text( $text, $level, $user ) {
	// Check if Group Accounts is active.
	if ( ! class_exists( 'PMProGroupAcct_Group_Member' ) ) {
		return $text;
	}

	// Get the member object for the user.
	$group_members = PMProGroupAcct_Group_Member::get_group_members(
		array(
			'group_child_user_id' => $user->ID,
			'group_child_level_id' => $level->id,
			'group_child_status' => 'active',
		)
	);

	// If there is not a group member, return the text as is.
	if ( empty( $group_members ) ) {
		return $text;
	}

	// Get the group member object.
	$group_member = $group_members[0];

	// Get the group object.
	$groups = PMProGroupAcct_Group::get_groups(
		array(
			'id' => $group_member->group_id,
		)
	);

	// If there is not a group, return the text as is.
	if ( empty( $groups ) ) {
		return $text;
	}

	// Get the group object.
	$group = $groups[0];
	

	return pmpro_get_membership_expiration_text( $group->group_parent_level_id, $group->group_parent_user_id, '' );
}
add_filter( 'pmpro_membership_expiration_text', 'my_pmprogroupacct_membership_expiration_text', 10, 4  );