prefix_add_group_to_field_name.php

<?php
/**
 * Display child products as meta in parent product
 */
add_filter( 'pewc_display_child_product_meta', '__return_true' );

/**
 * Add the group name to fields
 */
function prefix_add_group_to_field_name( $value, $field ) {
	if( isset( $field['group_id'] ) ) {
		$group_name = get_the_title( $field['group_id'] );
		$value .= ' - ' . $group_name . ' [#' . $field['group_id'] . ']';
	}
	return $value;
}
add_filter( 'pewc_filter_item_value_in_cart', 'prefix_add_group_to_field_name', 10, 2 );