Hi nauna,
First, make sure you are using the latest version of bootstrap-datepicker the library.
Download from the below link.
Download Bootstrap Datepicker
Create an embedded/inline datepicker to keep calender remain opened always.
Refer below code.
HTML
<div class="container">
<div class="date">
<input type="text" class="form-control" placeholder="Pick the multiple dates" />
</div>
</div>
<link rel='stylesheet' href='https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css' />
<script src='https://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js'></script>
<link href="bootstrap-datepicker.css" rel="stylesheet" />
<script src="bootstrap-datepicker.js"></script>
<script>
$(function () {
$('.date').datepicker({
multidate: true,
format: 'dd-mm-yyyy'
});
});
</script>
Screenshot