I think this would be best done by simply placing the "sub answers" in separate questions after Q1 and Q2 and use relevance or conditions to show/hide them as required.
You could use JavaScript to move the "sub answers" into Q1 and Q2 but it would get very involved and I think confusing for the respondent.
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Cheers,
Tony Partner Solutions, code and workarounds presented in these forums are given without any warranty, implied or otherwise.