Это то, что вы ищете? Я изменил идентификаторы на классы и использовал только один родительский идентификатор.
.row{
display:flex;
}
.col-3{
width:30%;
display:inline-flex;
}
.col-9{
width:70%;
display:inline-flex;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/js/bootstrap.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css" rel="stylesheet"/>
<div class="row" id="accordion1">
<div class="col-3">
<div class="panel-group" id="accordion1">
<div class="panel panel-default">
<div class="panel-heading">
<h4 class="panel-title">
<a data-toggle="collapse" data-parent="#accordion1" href=".collapseOne">Collapsible Group Item #1
</a>
</h4>
</div>
<div id="" class="collapseOne panel-collapse collapse in">
<div class="panel-body">Panel 1</div>
</div>
</div>
<div class="panel panel-default">
<div class="panel-heading">
<h4 class="panel-title">
<a data-toggle="collapse" data-parent="#accordion1" href=".collapseTwo">Collapsible Group Item #2
</a>
</h4>
</div>
<div id="" class="collapseTwo panel-collapse collapse">
<div class="panel-body">
<div class="panel-body">
<h2>Heading</h2>
<div class="panel-group">
<div class="panel">
<a data-toggle="collapse" data-parent="#accordion1" href=".collapseTwoOne">View details 2.1 »
</a>
<div id="" class="collapseTwoOne panel-collapse collapse">
<div class="panel-body">Details 1</div>
</div>
</div>
<div class="panel ">
<a data-toggle="collapse" data-parent="#accordion1" href=".collapseTwoTwo">View details 2.2 »
</a>
<div id="" class="collapseTwoTwo panel-collapse collapse">
<div class="panel-body">Details 2</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="panel panel-default">
<div class="panel-heading">
<h4 class="panel-title">
<a data-toggle="collapse" data-parent="#accordion1" href=".collapseThree">Collapsible Group Item #3
</a>
</h4>
</div>
<div id="" class="collapseThree panel-collapse collapse">
<div class="panel-body">
<div class="panel-group" id="accordion1">
<div class="panel panel-default">
<div class="panel-heading">
<h4 class="panel-title">
<a data-toggle="collapse" data-parent="#accordion1" href=".collapseThreeOne">Collapsible Group Item
#3.1
</a>
</h4>
</div>
<div id="" class="collapseThreeOne panel-collapse collapse in">
<div class="panel-body">Panel 3.1</div>
</div>
</div>
<div class="panel panel-default">
<div class="panel-heading">
<h4 class="panel-title">
<a data-toggle="collapse" data-parent="#accordion1" href=".collapseThreeTwo">Collapsible Group Item
#3.2
</a>
</h4>
</div>
<div id="" class="collapseThreeTwo panel-collapse collapse">
<div class="panel-body">Panel 3.2</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="col-9">
<div id="" class="collapseOne panel-collapse collapse in">
<div class="panel-body">Panel 1</div>
</div>
<div id="" class="collapseTwo panel-collapse collapse">
<div class="panel-body">
<div class="panel-body">
<h2>Heading</h2>
<div class="panel-group" id="">
<div class="panel">
<a data-toggle="collapse" data-parent="#accordion1" href=".collapseTwoOne">View details 2.1 »
</a>
<div id="" class="collapseTwoOne panel-collapse collapse">
<div class="panel-body">Details 1</div>
</div>
</div>
<div class="panel ">
<a data-toggle="collapse" data-parent="#accordion1" href=".collapseTwoTwo">View details 2.2 »
</a>
<div id="" class="collapseTwoTwo panel-collapse collapse">
<div class="panel-body">Details 2</div>
</div>
</div>
</div>
</div>
</div>
</div>
<div>
</div>