"image-select" – local links

Thank you for your help so far ??
I work with fields “image-select”. He wants to associate them with a specific theme.
I have this code:

array (
'id' => 'layout',
'name' => __ ('Icons', 'my-theme'),
'type' => 'image_select'
// Array of 'value' => 'Image Source' pairs
'options' => array (
'/img/icon-1.png' => '/img/icon-1.png'
'/img/icon-2.png' => '/img/icon-2.png'
'/img/icon-3.png' => '/img/icon-3.png'
'/img/icon-4.png' => '/img/icon-4.png'
)
)
)

I wish that the images were uploaded from local links. So I changed the file image-select.php adding get_stylesheet_directory_uri () line:

$tpl  = '<label class="rwmb-image-select"><img src="'. get_stylesheet_directory_uri() . '%s"><input type="%s" class="hidden" name="%s" value="%s"%s></label>';

and I put in the files of the page/post:

<?php $my_metabox_1 = rwmb_meta('checkbox_1'); ?>
<?php if ($my_metabox_1) echo '<img src="'.get_template_directory_uri() .''.rwmb_meta('layout').'">' ;?>

And everything works very well. ??
But … when I update the plugin is my change in image-select.php file will be overwritten.
Do you know any way that allowed to avoid overwriting this correction?

Thank you for your help.
Jack

https://www.ads-software.com/plugins/meta-box/