Hey Marijo
i struggled with the same issue lately - i think it's something that is never clear when following a couple of examples , that secondary datasources don't keep the data in store actually
http://www.infopathdev.com/forums/p/5373/26667.aspx#26667 shows another thread with some code in it
for good understanding
XDocument.DOM.SelectSingleNode("/my:myFields/my:RT_directreports").cloneNode(true); is refering to my (empty) repeating table in my main document
XDocument.GetDOM("Pricing").SelectNodes("/dfs:myFields/dfs:dataFields/tns:pricingResponse/tns:pricingResult/NewDataSet/Table"); is refering to my Oracle feedback through a webservice (secondary data thus)
it's a matter of like for like copying from one field to the other
watch out for my typo's in the code there, as Greg pointed out.
K