Design 1 in InDesign; export to PDF. Within the Print dialog of Acrobat, choose Print Multiple.
Design 1 in InDesign; make a new InDesign file and PLACE the earlier ID file into the new ID file (like a graphic). Option drag to duplicate and position 4 of them on page. Need to make a small adjustment? Edit Original.
If I do the second choice and make changes to the Original will the changes take place on the new page with the 4 copies?
Create in the first quarter of the page the postcard.
Select everything, use the content tool to select it, in the convoyer which appears now, select keep and link and place it 3 times on the page.
Changes have to be done in the original, updates are done when you open the link panel, select the change items and click the update button, or automatically after opening the file the next time.