var spread = new GC.Spread.Sheets.Workbook(document.getElementById("ss"),{sheetCount:3});
var sourceSheet = spread.getSheet(0);
var sheet = spread.getSheet(1);
var sourceData = [["Date","Buyer","Type","Amount"],
                  ["01-Jan","Mom","Fuel",74],
                  ["15-Jan","Mom","Food",235],
                  ["17-Jan","Dad","Sports",20],
                  ["19-Jan","David","Books",120],
                  ["20-Jan","Dad","Food",160],
                  ["21-Jan","David","Sports",15],
                  ["21-Jan","Kelly","Books",125]];
sourceSheet.setArray(0, 0, sourceData );
sourceSheet.tables.add('sourceData', 0, 0, 8, 4);
var layout = GC.Spread.Pivot.PivotTableLayoutType.compact;
var theme = GC.Spread.Pivot.PivotTableThemes.medium2;
var options = {showRowHeader: true, showColumnHeader: true};
var pivotTable = sheet.pivotTables.add("pivotTable_1", 'sourceData', 1, 1, layout, theme, options);
var groupInfo = {
    originFieldName: "Buyer",
    textGroup: {
        fieldName: "FamilyMembers",
        groupItems: {
             "parent": ["Mom", "Dad"],
             "children": ["David", "Kelly"]
        }
    }
};
pivotTable.group(groupInfo);
pivotTable.add("FamilyMembers", "FamilyMembers", GC.Spread.Pivot.PivotTableFieldType.rowField);
pivotTable.add("Buyer", "Buyer", GC.Spread.Pivot.PivotTableFieldType.rowField);
pivotTable.add("Amount", "Sum of Amount", GC.Spread.Pivot.PivotTableFieldType.valueField, GC.Pivot.SubtotalType.sum);
sheet.resumePaint();