I would be inclined to create a new, redacted, AIP: different parts of the file may lose their sensitivity at different rates, and the very process of producing different redacted copies over time, progressively revealing more information might well be of interest to future researchers. A slightly different case is where we receive a set of images from a company that has been licensed to do a digitisation and run a commercial service to provide access to the images. After a certain period of time the images may be resold to other commercial providers, where there is closed data in those images, a further set of redacted images (opening more of the data) will be prepared from time-to-time, and to get access to the newer set, the secondary providers would have to purchase them again. If for some reason, they perhaps opted to purchase only every other set of images or similar, there arises a possible situation where they discover an issue with some proportion of the earlier images, and we ned to resupply those images to them, making sure (in effect) that they don't also receive the additional information which they haven't purchased. We can only be sure of doing that if each set is a separate AIP.