In a certain table control SAP offers a button that copies a line. Unfortunately, the new line is at the end of the table, so that the user has to scroll down in order to see it. Is it possible to rearrange the table control lines so that the new line is straight after the one that has just been copied?

No, GuiXT offers no way to rearrange the table lines. Since the SAP application expects a certain ordering, and addresses the table control line with a fixed index, this would interfere with the application logic.

What you perhaps can do is to add a new button that copies the line and then scrolls down automatically.