Currently, form extraction does not allow you to filter documents when performing an extraction. It would be great if you can order a form extraction based on the different columns produced or by the name of the document uploaded.
What would be even better would be to combine document matching and form extraction. For example being able to document match one element of a document (e.g. reference no.) and then use form extract on those items picked up from the document match (a fixed point in other words) to populate the following columns with information from the same document in the same order/row, so that it all lines up.
This would not only allow you to match up the right documents to your samples using a document match but you could then extract all relevant information in the following columns without the need to reorder or manually snip in each item.