Implement nested mail merge - creating mail merge reports using master-detail tables in a data source.
Typical example of this is creating an invoices with mail merge, where each invoice contains a list of items.
Workaround: for some scenarios creating custom merge field which evaluates to Table could simulate this behavior:
http://www.telerik.com/forums/merge-reports#lUdH39ww00SnEhTLLlrXwA