Change a review group's factor. Every unsubmitted row the factor fits takes it, except a row a reviewer gave its own factor, which keeps it; rows it does not fit keep theirs. The group becomes the reviewer's, and a group keyed by a producer skill whose key was answered is remembered for the organization. Takes the analysis version the review was read at and answers with the new one. Refused while any document job runs for the upload. The group key is percent-encoded as one path segment.