C# - Nested Repeater With Child Repeater In A User Control?

Edit: I have a working solution already - I would just like to know why my original attempt didn't work. My original attempt is the code below.

I'm using the approach I found here:[URL] 306154 to implement a nested Repeater. Each parent item has one or more children items (the point of having the nested Repeater) with a dropdown horizontally aligned to each child item. In an effort to re-use the nested part of the Repeater I wanted to develop that piece as a user control but couldn't get it to work. I am wondering if it is even possible and if so how?

Here is my user control apsx:

<asp:Repeater ID="NestedRepeater" runat="server">
....
<ItemTemplate>
<tr class="text" id="RepeaterItemRow" runat="server">
<td>
<%#DataBinder.Eval(Container.DataItem, "Name") %>
</td>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
</td>
</tr>
</ItemTemplate>

And here is my code behind for the user control. I noticed when I debugged NestedDataSource was null even though in the parent page load the data is there:

public DataSet NestedDataSource
{
get;
set;
}
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
NestedRepeater.DataSource = NestedDataSource;
NestedRepeater.DataBind();
}
}

In the parent Repeater in the `<ItemTemplate> I have:

<asp:RepUC ID="NestRep" runat="server" NestedDataSource='<%#((DataRowView)Container.DataItem).Row.GetChildRows("nestedrel") %>'>

And finally the page code behind:

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
BuildWBS();
}
}
private void BuildPage()
{
DataSet ds = new DataSet();
ds = DataAccessLayer.GetData("System");
ds.Relations.Add("nestedrel", ds.Tables[0].Columns["Id"], ds.Tables[1].Columns["ParentId"]);
ParentRepeater.DataSource = ds;
ParentRepeater.DataBind();
}

The page loads but nothing relating to the repeater appears on the screen. So, can you see anything wrong with what I have? Is the way I tried doing this even possible?