Hm, it actually kind of seems like he's using rules because it's copying to all rows.
Claire, are you using the "Copy value to field" rule? If so, I think you will want to remove this and look into code to copy the row from one table to another. You will want to look at the IXMLDOMNode.appendChild() method. There is also some code in this HowTo that you might find useful (just skip the HowTo, and look through the code):
http://infopathdev.com/howto/tutorials/default.aspx?i=80c11a66b08a4572bc2b17f391319a0fHowever, I'm wondering why you are doing this. It kind of sounds like you could have two copies of the same table on the view and the checkbox simply determines whether or not it displays in the other or not. Could you explain a little more about your situtation so we can give you the best advice?
Hope this helps!
Matt Faus / Microsoft InfoPath MVPQdabra® Software / Streamline data gathering to turn process into knowledge