Generally, there is no standard method to use hierarchical data, i. e. the data that is organized into a tree-like structure (see the Hierarchical model) as a datasource for the XtraReport. However, you can manually implement an effective and generic algorithm that performs data transformation from the hierarchical structure to the relational one.
This example demonstrates how it can be done. The core of this example is the RepTreeListHierarchicalDataRelationships.DataSetHelper.HierarchicalListToDataSet<T>() generic method, which transforms a List<T> to the DataSet. Also, please take special note of the fact that the RepTreeListHierarchicalDataRelationships.Form1.GenerateReport() method, which dynamically generates a report, based on the resulting DataSet.