[Plugin: NextGEN Gallery] Insert Button Not Working with Multi-Site

I am using a multi-site setup and because I am using the domain mapping plugin, several buttons in the post/page editor do not work because they look to the original domain to call up the function. When I click on the NextGEN gallery insert button, all that comes up is a blank box. I found a workaround with the TINY MCE buttons by switching out

$plugpath = WP_PLUGIN_URL . ‘/tinymce-advanced/mce/’;

with

$plugpath = $blog_url . ‘/wp-content/plugins/tinymce-advanced/mce/’;

Is it possible to make an edit like this in the plugin files for NextGEN?

Thanks!

https://www.ads-software.com/extend/plugins/nextgen-gallery/