We have exactly the same problem here....
Where does Maven determine the order for reports?

Execution order of plugin's is something that has had quite a bit of discussion about but I'm afraid I have no specific URLs to let you catch up with the current thinking re this.

I noticed something strange and made a test. I suspected plugins/reports were being executed in alphabetic order (first by groupId, then by artifactId) and so they are!

For example, I have a problem generating QALab reports in child projects, because QALab plugin was always executed before the reports that generate data. Then I noticed the reports were generated almost in the order I specify them (I use the above alphabetic order, expept for the QALab plugin, that is the last one). Then I imagined that maybe that happens because all my reports are from org. groups while QALab belongs to net..

I tested it by creating a dummy plugin by renaming the groupId of a QALab report plugin to zzz.net.objectlab and deploying it to my local repository. Then I changed my root dependency to this new one and magic, IT WORKS.

I suspect someone is using a sorted collection (tree set, etc). Some display-beautifuly-list is messing things up.

Patch against 2.1.x with unit test

mergeReportPluginLists behavior copied from mergePluginLists which was fixed in related issues

also for some reason, as commented in the unit test, the configurations of reports don't seem to be merged

applied

using 2.1 the order is still not respected, I define in the parent a couple of report plugins and when the site phase is executed on the child, the order is not respected

Carlos, was this patch properly applied to 2.1?

I applied it, and created an IT. Please compare your use case to the IT, and file a new issue against 2.1.0 with a sample project if there is a problem.