Is there a good way to edit the pages so they don’t get over written on each update of the script?

I’ve added the code above to image-store/theme/ims-image.php however its not displaying anything.

I tried echo $imStore->store_subnav(); and echo $ImStore->store_subnav(); but neither display the order form.

I get this error though:

Order Form Fatal error: Call to a member function store_subnav() on a non-object in /var/www/vhosts/xxxx.co.uk/clients/wp-content/plugins/image-store/theme/ims-image.php on line 45