Dear Shamim,
Thank you very much for the help you give me.
To add the date selection field, I added the following code, but nothing is displayed.
Can you tell me what I should change?
add_filter( ‘fep_form_field_output_date’, function( $fields ){
	$fields[‘cus_fep_test’] = [
		‘type’	=> ‘date’,
		‘where’    => ‘newmessage’,
		‘priority’	 => 12,
		‘label’	=> ‘Test’,
	];
	return $fields;
});
add_action( ‘fep_action_message_after_send’, function( $message_id, $message, $new_message ){
	if ( ! empty( $message[‘cus_fep_test’] ) ) {
		fep_add_meta( $message_id, ‘cus_fep_test’, $message[‘cus_fep_test’], true );
	}
}, 10, 3);
add_action( ‘fep_display_after_message’, function(){
	if ( $cus_fep_test = fep_get_meta( fep_get_the_id(), ‘cus_fep_test’, true ) ) {
		echo ‘<div>Test :      ‘; echo esc_html( $cus_fep_test ) . ‘</div>’;
	}
});