gp-nested-forms-force-parent-merge-tag-on-submission.php

<?php
/**
 * Gravity Perks // Nested Forms // Force {Parent} Merge Tag Replacement on Submission
 * http://gravitywiz.com/documentation/gravity-forms-nested-forms/
 */
add_filter( 'gform_entry_post_save', function ( $entry, $form ) {
	$pattern = '/{Parent\:(.+)}/i';

	foreach ( $form['fields'] as &$field ) {
		if ( $field->get_input_type() == 'form' ) {
			$child_form_id   = $field->gpnfForm;
			$child_form      = GFAPI::get_form( $child_form_id );
			$child_entry_ids = explode( ',', rgar( $entry, $field->id ) );

			foreach ( $child_form['fields'] as $child_field ) {
				if ( is_array( $child_field->inputs ) ) {
					foreach ( $child_field->inputs as $input ) {
						if ( empty( $input['defaultValue'] ) ) {
							continue;
						}

						preg_match( $pattern, $input['defaultValue'], $match );
						if ( $match ) {
							$value             = rgar( $entry, $match[1] );
							$input_id          = implode( '.', array_slice( explode( '.', $match[1] ), 1 ) );
							$child_entry_input = $child_field->id . '.' . $input_id;

							foreach ( $child_entry_ids as $child_entry_id ) {
								GFAPI::update_entry_field( $child_entry_id, $child_entry_input, $value );
							}
						}
					}
				} else {
					preg_match( $pattern, $child_field->defaultValue, $match );
					if ( $match ) {
						$value = rgar( $entry, $match[1] );
						foreach ( $child_entry_ids as $child_entry_id ) {
							GFAPI::update_entry_field( $child_entry_id, $child_field->id, $value );
						}
					}
				}
			}
		}
	}

	return $entry;
}, 11, 2 );