Add Nested Query to Existing Nested Query in Report Scripted Data

I have had success adding a nested query to an existing datasource using a scripted datasource, but what I have not been able to do is to add a nested query to an existing nested query.

I have a Query Data Source "Parent Data". It has a Nested Query called "ChildData". When I execute the following:

from import QueryResults

parentData = data['ParentData']
nestedResults = parentData.getNestedQueryResults()
childData = nestedResults['ChildData']

testHeader = ['col1', 'col2']
testData = [[1,2],[3,4]]
testData = system.dataset.toDataSet(testHeader, testData)

childData.addNestedQueryResults('TestData', [QueryResults(testData)])

I get the error "AttributeError: 'array.array' object has no attribute 'addNestedQueryResults'"

I am able to add the testData QueryResults directly to ParentData, but not to ChildData
ie parentData.addNestedQueryResults('TestData', [QueryResults(testData)]) works properly

OK, as is usual for me I seem to have figured out the issue as soon as I look for help.

nestedResults['ChildData'] seems to give me a list of QueryResults so I needed nestedResults['ChildData'][0] to access my Nested Query