sorry, I think I had a brain blip; indexmatic won't let you index by grep. However, you could use Find/Change to apply a character style (use a character style that does nothing, applies no formatting, perhaps) to all the text using GREP. Then indexmatic could find text tagged with those styles.

As I noted earlier: Shift-click when you place.

Here are some clever solutions:

https://creativepro.com/hig…..-color.php

and look at the script by Thomas Silkjaer linked to halfway down this post:

https://creativepro.com/thi…..mber-8.php

As I noted earlier: Shift-click when you place.

I wonder if you could use the IndexMatic script to do this, based on a GREP expression.

There are one bazillion things that people want to set up in ID (for the same reason you provide) but which require Acrobat. But it just won't work that way. Very frustrating. You will like need to do it in Acrobat, but check out this helpful blog post when it comes time to update the file:

https://creativepro.com/des…..ervice.php

I suggest going doing a search on indesignsecrets.com for XML. There's lots of stuff on the site. Check out Jim Maivald's book on XML for InDesign, too.

However, my philosophy is clear on this: If there is any reasonable way to do a project in InDesign that does not involve XML, you should take that route. XML is wonderful, but it's not for the faint of heart or the sloppy of mind, and there are many other better solutions for the problems people are trying to tackle.

I don't have a great answer for this, but I have a sense that it might be easier to use Data Merge to create a PDF file just 1-up… that is, each page just has one postcard. Then impose the PDF with one of the many imposition programs on the market, or place the pages of the PDF back into a new ID file in the form you want them.