Bootstrap Treeview relation between (parent or child ... ) and checkbox : how set item checkbox when i click on element span which have this checkbox?

I added checkboxes to my treeview, but there is no relationship between the node (parent or child...) and the added checkbox

I want when I click on the node or at the input I checked checkbox and I open the list of children of this node at the same time,

and if I click again on the node (parent or child ...) or input I uncheck input and I close the list of children of this node

Here is my code

$(function () {
    $('.tree li:has(ul)').addClass('parent_li').find(' > span').attr('title', 'Collapse this branch');
     var extra = $(".tree li.parent_li > span")
    .parent("li.parent_li")
    .find(" > ul > li");
  extra.hide("fast");
    
    $('.tree li.parent_li > span').on('click', function (e) {
        var children = $(this).parent('li.parent_li').find(' > ul > li');
        if (children.is(":visible")) {
            children.hide('fast');
            $(this).attr('title', 'Expand this branch').find(' > i').addClass('icon-plus-sign').removeClass('icon-minus-sign');
        } else {
            children.show('fast');
            $(this).attr('title', 'Collapse this branch').find(' > i').addClass('icon-minus-sign').removeClass('icon-plus-sign');
        }
        e.stopPropagation();
    });
});

.tree {
    min-height:20px;
    padding:19px;
    margin-bottom:20px;
    background-color:#fbfbfb;
    border:1px solid #999;
    -webkit-border-radius:4px;
    -moz-border-radius:4px;
    border-radius:4px;
    -webkit-box-shadow:inset 0 1px 1px rgba(0, 0, 0, 0.05);
    -moz-box-shadow:inset 0 1px 1px rgba(0, 0, 0, 0.05);
    box-shadow:inset 0 1px 1px rgba(0, 0, 0, 0.05)
}
.tree li {
    list-style-type:none;
    margin:0;
    padding:10px 5px 0 5px;
    position:relative
}
.tree li::before, .tree li::after {
    content:'';
    left:-20px;
    position:absolute;
    right:auto
}
.tree li::before {
    border-left:1px solid #999;
    bottom:50px;
    height:100%;
    top:0;
    width:1px
}
.tree li::after {
    border-top:1px solid #999;
    height:20px;
    top:25px;
    width:25px
}
.tree li span {
    -moz-border-radius:5px;
    -webkit-border-radius:5px;
    border:1px solid #999;
    border-radius:5px;
    display:inline-block;
    padding:3px 8px;
    text-decoration:none
}
.tree li.parent_li>span {
    cursor:pointer
}
.tree>ul>li::before, .tree>ul>li::after {
    border:0
}
.tree li:last-child::before {
    height:30px
}
.tree li.parent_li>span:hover, .tree li.parent_li>span:hover+ul li span {
    background:#eee;
    border:1px solid #94a0b4;
    color:#000
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<link href="https://netdna.bootstrapcdn.com/twitter-bootstrap/2.3.1/css/bootstrap-combined.min.css" id="theme" rel="stylesheet">
<div class="tree well">
    <ul>
        <li>
            <span>  <input type="checkbox" id="test1" name="test1">  Parent</span> 
            <ul>
                <li>
                    <span><input type="checkbox" id="test2" name="test2"> Child</span> 
                    <ul>
                        <li>
                            <span><input type="checkbox" id="test3" name="test3"> Grand Child</span> 
                          <ul>
                        <li>
                            <span><input type="checkbox" id="test3" name="test3"> Grand Grand Child</span> 
                           <ul>
                        <li>
                            <span><input type="checkbox" id="test3" name="test3"> Grand Grand Grand Child</span> 
                        </li>
                    </ul>
                        </li>
                    </ul>
                        </li>
                    </ul>
                </li>
                <li>
                    <span><input type="checkbox" id="test4" name="test4"> Child</span> 
                    <ul>
                        <li>
                            <span><input type="checkbox" id="test4" name="test4"> Grand Child</span> 
                        </li>
                        <li>
                            <span><input type="checkbox" id="test5" name="test5">Grand Child</span> 
                            <ul>
                                <li>
                                    <span><input type="checkbox" id="test6" name="test6"> Great Grand Child</span> 
                                    <ul>
                                        <li>
                                            <span><input type="checkbox" id="test7" name="test7">Great great Grand Child</span> 
                                        </li>
                                        <li>
                                            <span><input type="checkbox" id="test8" name="test8"> Great great Grand Child</span> 
                                        </li>
                                     </ul>
                                </li>
                                <li>
                                    <span><input type="checkbox" id="test9" name="test9">Great Grand Child</span> 
                                </li>
                                <li>
                                    <span><input type="checkbox" id="test10" name="test10"> Great Grand Child</span> 
                                </li>
                            </ul>
                        </li>
                        <li>
                            <span><input type="checkbox" id="test11" name="test11"> Grand Child</span> 
                        </li>
                    </ul>
                </li>
            </ul>
        </li>
        <li>
            <span><input type="checkbox" id="test12" name="test12"> Parent2</span> 
            <ul>
                <li>
                    <span><input type="checkbox" id="test13" name="test13"> Child</span> 
                </li>
            </ul>
        </li>
    </ul>
</div>

Here's a JSFiddle link :https://jsfiddle.net/daizdev/q5hwg0yj/13/