Front End PM Page created with add_rewrite_endpoint

I’m integrating Front End PM with WooCommerce, and have created an extra page(tab) named ‘messages’ in the WC account management section with add_rewrite_endpoint.

Since there is no associated page to select in the ‘Front End PM Page’ setting, I’ve selected the WC ‘My account’ page and changed fep_query_url_without_esc to:

$url = add_query_arg( $args, get_permalink( fep_page_id() ) . 'messages/' );

Is there a better way of doing this e.g. from my theme functions.php? Sorry if this is basic!