Upgrading to 2.7 causes error in the presentation of adapted header.php

Hi,
First I used Enfold 2.54. There I create a Child Theme for the adaption of the theme.
I put the file header.php to the folder of the child theme and added there the following code:

<div id='header_meta' class='container_wrap container_wrap_meta'>
    .....
    if($phone) echo "<div class='phone-info {$phone_class}'><span class='hotline_text'>Umzugshotline</span><span class='hotline_phone'>{$phone}</span><img src='http://www.schoeffl.at/wp_site/wp-content/uploads/Lkw_middle.png'><input type='button' onClick='window.location=\"http://www.schoeffl.at/wp_site/kontakt/anfrageformular\"' value='Anfrage' style='float:right;cursor:pointer;' class='inquiry' /></div>";
...

After upgrading the theme the header.php of the original theme has been changed. So that the section above now is found in
/includes/helper-main-menu.php.

When I copy this file into the folder of the child theme, the changes of this will not apply. I hope, that I don’t have to change this in the original theme code, and I can copy it to the child theme.

Thanks, Daniela