Can pdf and djvu files share annotation files in Okular?

I have a pdf and a djvu files. One of them is created by converting the other.

1. If I have made some annotations to the pdf file in Okular, can the djvu file share the annotations with the pdf file?

If I am correct, annotations saved to an .okular archive file for a pdf file can only be used standalone, so the djvu file can't use the annotations.

Also I find that the annotations are saved by Okular automatically under a home dir ~/.kde/share/apps/okular/docdata (I am using Gnome and Ubuntu).
the name of the annotation file is some number followed by the filename of the pdf file and by ".xml".
What is the "number"? Is it some hash value of the filename of the pdf file?

I did some trial to make the xml annotation file work with the djvu file (the djvu file was created from the pdf file by pdf2djvu).
I rename the xml file so that the djvu file can find it, by the following two steps:

(1) firstly, create a dummy annotation file for the djvu file, and remember the "number" from the filename of the dummy annotation file.
delete the dummy annotation file for the djvu file,

(2) then, change the annotation xml file for the pdf file to one for the djvu file:
replace the number in the name of the xml file for the pdf file, with the new number from the deleted dummy xml file for the djvu file.
change "pdf" to "djvu" in the file name of the annotation file

Now the annotations created for the pdf file work for the djvu file, but the annotations' font size in the djvu file looks much smaller compared to the font size of the original text. That is bad.

2. Conversely, if Ihave made some annotations to the djvu file in Okular, can the pdf file share the anoations with the djvu file?

If there is no convenient way of sharing annotations between pdf and djvu files, can I make a feature request?

Thanks.

No two different files can't share annotations (well they do if they have the same size and filename)

The number is the file size, probably you can change the pdf annotations file to match the djvu file size and name and it should most probably work.

"If there is no convenient way of sharing annotations between pdf and djvu files, can I make a feature request?"

You can use bugs.kde.org to ask for this feature but you'll have to be very convicing because i don't see the point of it at all.