I'm now working on a second transform to be applied to the result of the first. This one already detects sale-to-self situations (although it doesn't find any -- waiting for some known data from JS-R to see why) and possible family sales. I'm now working on building the transaction chains, but I'm not sure whether this can actually be done with XSLT or not, because you need to keep a tally of which items have already been processed, and I can't yet figure out a way to do that.