xlsx writing - where specified?
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I'm trying to write a parser in python at the moment, that reads nessus reports and generates xlsx files.

I've done that without any too big problems, because I've taken one example file and changed that. But now I've wanted to add an extra sheet. 
The sheet also exists later on in the document, but everything I want to write onto that page goes into sheet3.xml, but that somehow is not included on the third page. How (which XML statements ) and where (which file) do I need to specify so that what I write in sheet3.xml finds its way onto relation id rId=5 ?

