A "Data" band can contain one or several nested "Data" bands. This allows building a master-detail-detail report type. To do this, call the "Configure Bands" window, right click on the master "Data" band and add a detail "Data" band to it. Repeat this procedure in order to add the second detail band:
In this way, it is possible to add an unlimited number of detail bands to the master "Data" band. An example report structure can be like this (this is just an example; it only demonstrates the abilities of FastReport):
