It looks like there's a limit of five frame positions for Picture-in-Picture. Is there any sort of plugin, extension, or ? that can extend that so you can put in, say, 12?
The limit is what you can reasonably actually see.
PiP is simply resizing the images using the Size/Position effect. Zoom out, move the box, adjust the left and top positions in the counters, etc.
Add in another image or video on a higher track, below the others that you have. It will be full-screen. Go to Size/Position, make sure the image is selected on the timeline. You should have a dashed line around the image. Resize it and move it with the mouse. Look at the Size/Position counters. Click on another image - look at the counters. Move, resize, etc.
If you want everything worked out to fit, then get out your calculator.
See this tutorial in German. Translate it to English. Walter has a table in the pdf file to guide you with size and position of windows, depending on how many that you want.
Then you can learn to keyframe if you want to animate any of these.
John CB
Great! Thanks very much.