Button to link to the same page on another omeka installation

Hello,
I have two omeka sites installed on two subdomains (with two different databases but the entries match) :
- subdomain1.domain.org
- subdomain2.domain.org

I would like to add a button on every item show page of my omeka installed on subdomain1, to link towards the same item on subdomain2.

For example, on the page subdomain1.domain.org/items/show/153, I would like to add a button that links to the page subdomain2.domain.org/items/show/153

I use the seasons theme, I guess I need to add something in the themes/seasons/items/show.php file, but I don't know how to do it.

Could anyone provide me guidance?

Thanks,
François.

The basics might work something like getting the url for the current item, then replacing subdomain1 for subdomain2 with str_replace. This will get you the current url on an items/show page:

<?php
    $url = record_url($item, 'show', true);
?>

After that replacement, you can add the link wherever in the items/show.php file.

Thank you it worked!