Since you are pointing to same database, you can use combine two query into single query and fetch it and bind it to the datasource.
It will be easy for you.
select B1.blah1,B2.blah2 from blah1 B1,blah2 B2
Use the below code instead of yours
protected void Page_Load(object sender, EventArgs e)
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["BasketballConnectionString1"].ToString());
SqlDataAdapter adapter = new SqlDataAdapter();
query = "select B1.blah1,B2.blah2 from blah1 B1,blah2 B2";
SqlCommand = new SqlCommand(query, conn);
adapter.SelectCommand = new SqlCommand(query, conn);
reader = SqlCommand.ExecuteReader();
GridView4.DataSource = reader;
Hope this would help you a bit.