Please download this sample before reading the rest of this FAQ. Looking through the sample will help follow the description.simpledata2.zip
What this boils down to is this:
1) Load both Master and Details queries in a dataset.
2) Bind the master data grid to the Master dataset table.
3) Create a relationship that describes how the two tables relate to each other. A primary key foreign key relationship is defined by two attributes.
The primary key column in the master table
The foreign key column in the details table
The created relationship is added to the dataset.
4) Set the data member for the details table to be the name of relationship that was added to the dataset.