First of all, you cannot make changes in standart reports. You cannot change the dataitem, the code behind. But it’s possible to change the layout by creating a custom layout with BC using MS Word or the RDLC Report Designer. There you can use the available fields from the standard report. It’s not possible to add new fields.

To add new fields, additional code, following has to be done: Copy the existing Standard report, create a new report extension and add the dataitem and the code to the extension by using the “AL Object Designer” in Visual Studio Code.

For version 15 or newer:

• Start with a new extension in BC
• Install or use installed “AL Object Designer”
• Download symbols from a sandbox
• Open the “AL Object Designer”: type “AL Object Designer” in the search box.
• Search for the report, click on the report name. A new tab will be opened, the code incl. dataitem of the report is then shown.
• Copy the code to the new .al file, change ID and name. Make then the needed changes, add fields and code, what ever, save.
• Upload and publish the extension to the sandbox.
• Goto “Report layouts/Custom layouts”, download the original layout and upload it to the new report, press update layout.
• Download the report layout from the new report, change the layout according to your needs, add e.g. the new fields.
• Upload the changed report layout, select the new report in report selections and use it, where needed.  

For older Releases do the following: Install a local version of BC on your laptop or use a docker container for that. Export the report object using finsql as .txt file. Then convert it to AL code using the Txt2Al conversion tool.