Is there a way to tell server or client side script on my website that your modals are visible or not?

Yes, there is. Please run the following JavaScript in your Parent page:

There is a JavaScript event that you can subscribe and you will be notified when one of the campaigns is popuping up.

$('html').on('optimonk#campaign-show', function(event) {
     console.log('event: ', event);
     console.log('event.parameters: ', event.parameters);
 });