I needed to have ASP.NET report with DataRepeater and nested data bound user control.
The similar approach is used in  ASP.NET Reports Starter Kit  with datagrid nested in datalist itemtemplate.

       <asp:datalist id="CategoriesList" runat="server" >
                <itemtemplate>
                                <asp:datagrid id=Datagrid1 runat="server"  DataSource=''<%# GetDetails(DataBinder.Eval(Container.DataItem, "CategoryID")) %>'
                                </< FONT>asp:datagrid>
                </< FONT>itemtemplate>
                <headerstyle cssclass="ReportTitle"></< FONT>headerstyle>
            </< FONT>asp:datalist>
 So my markup should be like this: 

<%@ Register Src="MyUserControl.ascx" TagName="MyUserControl" TagPrefix="uc1" %>

<asp:Repeater ID="Repeater1" runat="server">

<ItemTemplate>

<uc1:MyUserControl  DataSource=<%# GetDetails(DataBinder.Eval(Container.DataItem,"PatronId")) %>

 ReportId= <%# ReportID %> id="patronNotice" runat="server" >

</uc1:OverdueNotice>

</ItemTemplate>

</asp:Repeater>

I’ve created DataSource property and on DataBinding event used it to populate my UserControl data.
But it didn’t work. DataBinding event occurred earlier than DataSource was set from DataBinding expression and  DataSource=Nothing.

I’ve read carefully the DataBinding documentation and understood that
DataBind can be called more than once during the same request and it is important to re-do binding if DataSource property has been changed.
So I had to implement Data Bound User Control class to resolve the issue.