[tgiladi]

Hi,
My problem seems kind of specific, and I couldn't find an answer so far. I hope someone could help with this:
I am using the polish feature in Calibre to add a Jacket page to my books, so I could read the book comments. After polishing, I am manually editing the Jacket.xhtml file, to add some data about the author, their picture etc.
This works very well when I am uploading the resulting epub file to various e-reading apps (e.g. Readera, Google Play Books etc.). But if I try to send it to my Kindle via email or using the Send to Kindle web service or any other method, the formatting of my modified jacket.xhtml becomes corrupted.
I think it has to do with the conversion into .kfx that Amazon is doing.
So, I tested what happens when I use Calibre to convert my epub into AZW3, polish it again, modify the jacket.xhtml as needed and then sideload the AZW3 onto my Kindle Oasis via cable, using Calibre.
The result was excellent, and I could see my formatting of the jacket.xhtml as intended.
However, this method is not adding the book to my personal document library on Amazon, meaning it would not sync with my other devices running the Kindle app (e.g. phone, tablet).

So, the question is: is there a way to both keep my custom formatting of the jacket.xhtml file AND also have the book sync across devices?
Or am I doomed to have to choose between nice format and sync?