Here's what I found out by testing:

1. Reports are stored one file per report in the folder “C:\Skyline DataMiner\Webpages\Reports\Templates\”. The naming is “[Report name as shown in the app].asp”.
2. The file “C:\Skyline DataMiner\Webpages\Reports\Templates\Templates.xml” contains the list of reports as shown in the main view of the Reports app. It has to be updated or replaced with the one containing all needed reports.
3. The file “Templates.inc.asp” and subfolders “styles” and “tmp_img” can be left untouched.

This is the procedure that worked in my test setup to migrate the reports:

1. Copy the required reports from “C:\Skyline DataMiner\Webpages\Reports\Templates\” on the source DMA to the target DMA.
2. If all reports are migrated and the target DMA has no existing reports, copy the file “C:\Skyline DataMiner\Webpages\Reports\Templates\Templates.xml” to the target DMA.
   If more granularity is required, edit the file on the target DMA to include information on all reports that are being added. You might want to use an XML plugin to display the XML body in a human readable way.
3. Run “System Center > Tools > synchronization > Synchronize > This DataMiner Agent” to distribute the imported report files across the DMS.
4. Run “System Center > Tools > synchronization > Synchronize > File > C:\Skyline DataMiner\Webpages\Reports\Templates\Templates.xml”, as this file is not synchronized automatically.
5. If the Reports & Dashboards app shows an error, run “C:\Skyline DataMiner\Tools\dcomConfig.exe” as Administrator (this has to be done on every DMA in the target DMS).
6. Possibly, an IIS restart might be required to update the app.

Please note, I would like to keep this question open as what worked for me might not be the best way to do it or might cause some issues I'm not aware of. So an expert advice would be greatly appreciated. Thanks!