lvov,
три кнопки, для одного окна в моём понимании это так.
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
</style>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/magnific-popup.js/1.1.0/magnific-popup.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/magnific-popup.js/1.1.0/jquery.magnific-popup.min.js"></script>
<script>
$(function () {
$('.open-popup-link').magnificPopup({
type:'inline',
midClick: true
});
});
</script>
</head>
<body>
<a href="#test-popup" class="open-popup-link">Show inline popup</a>
<a href="#test-popup" class="open-popup-link">Show inline popup</a>
<a href="#test-popup" class="open-popup-link">Show inline popup</a>
<div id="test-popup" class="white-popup mfp-hide">
Popup content
</div>
</body>
</html>