Did you try putting a portal inside the popover? When the popover is itself located inside a portal, a portal cannot be placed inside the popover. That's the equivalent of putting a portal inside a portal and this is something not currently possible.
What you can do is move the popover button out of the portal and use the "hide when" setting for it to make it always invisible. You can then give the Popover's frame an object name and a button placed in the portal row can use Go to Object to open the popover.
Then it's a matter of setting up relationships and setting match field values so that this single popover will display the correct set of related records for the portal record where you clicked the portal row button.
This then becomes an interesting extension of a "master detail" pair of portals such as those described here: Need layout solution for nested portals...
The detail portal is what you would place inside the popover frame.
Maybe I didn't explain it right, Here are the screens for what I'm trying to accomplish.
Ok, that field counts as a field inside the portal. It thus has the same limitation that a container field placed inside the portal row has--interactive container fields aren't interactive when inside a portal row.
The method that I described can be modified to handle this same situation, but you link to the primary key value of the selected portal row record to show that record's PDF in a popover placed outside the portal.
Yeah, that was my thinking.
I created a Modal Layout that pops up in a new window when they click on the button. That seems to give me "BASICALLY" the same functionality and the users are happy. (Ok, Maybe not in a "You complete me" sort of way, but content)
That's definitely a way that I've used, especially before popovers. The main draw back in is that you can get some "funky window behavior" on windows platforms. I'm not a big fan of the "window inside a window" look that you get when windows are not maximized, but when you maximize windows, opening a new window resizes all of the other open windows--often requiring extra scripting to keep them from re-sizing to really undesirable dimensions...