More then 1 Modal on site

In the footer of this site: https://www.exactech.fr/ I would like a Modal to popup based on links in footer to tell user they are leaving the site. I saw how to do that in the FAQs

How can I make Modal Dialog open when I click on a button or a link?

Add the onclick property to your link or button code and call the modal_dialog_open() function.

<a href="#" onclick="modal_dialog_open();" title="Learn More">Learn More</a>

<button onclick="modal_dialog_open();">Open Modal</button>

But we already are using a Modal on some other pages. How can I create another Modal in the settings area? I dont see anywhere to “add new” or “create new”

The page I need help with: [log in to see the link]