I'll just push my opinion one more time....
An "update" is a new appraisal.
What the update-process allows us to do is incorporate those relevant findings from a previous appraisal into a new appraisal. We don't have to re-do what we've already done if there is no reason to re-do it.
The reporting option we use is unrelated to the old appraisal. The old appraisal is simply data and analysis that applies to the new assignment. One could have a very detailed "appraisal report" incorporated, referenced, etc., into the new appraisal.
What defines the new appraisal's reporting format is how its results are reported. Those results are either "summarized" or "stated". If "summarized", then the new report is an "appraisal report". If stated, then the new appraisal's communication is consistent with a restricted report.
The reporting options create the minimum reporting requirements.
A written appraisal report must be compliant with one of the two reporting options.
What has been incorporated into a new appraisal does not determine what reporting option the new appraisal complies with. That the new appraisal's analysis is stated or summarized does determine what reporting option is used.
Simply checking this box:
Without providing the summary outlined below:
Does not meet the SR2-2 standard.
Checking the box only does meet this SR2-3 (restricted appraisal report) requirement:
If one only checks the box, one has stated the results/conclusion of the new appraisal. That isn't consistent with an appraisal report's reporting requirements, regardless if the original appraisal report used as part of the update process has summarized all of its findings.