Changing Child Table's properties inside a Nested Table

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C#

Theres 2 tables in this dataset. They have a relation between a column called "Reporting Date"

When I take this dataset and bind these to a grid I can access the first table through Grid.PrimaryGrid.Columns but I can't access the second table which is nested to the first table.

For the table that is displayed as the "Primary Grid" you can drop down and see nested records from the second table but I cannot edit the second tables headers. How do I edit the second table's headertext?
for the first table I can do this to change the header text for each specific column:

Grid1.PrimaryGrid.Columns["SoldOz"].HeaderText = "Total Sold Oz";

for example I have the following code:

//DATASET
DataSet DSHourly = new DataSet();

//TABLES
DataTable TBCondensed = DSHourly.Tables.Add("TBCondensed");
DataTable TBHourly = DSHourly.Tables.Add("TBHourly");

//RELATION
DSHourly.Relations.Add("1", DSHourly.Tables["TBCondensed"].Columns["ReportingDate"], DSHourly.Tables["TBHourly"].Columns["ReportingDate"], false);

//BINDING TO GRID
Grid1.DataSource = DSHourly;
Grid1.DataMember = "TBCondensed";

//HEADER TEXT FOR PRIMARY TABLE
Grid1.PrimaryGrid.Columns["SoldOz"].HeaderText = "Total Sold Oz";