[slowsmile]

@BKh...I think the easiest way for you to create a doc TOC and Nav TOC(device TOC) is to load your azw3 version into Calibre and then click on Edit Book. Then click on the Edit TOC button in the Calibre editor toolbar and this will bring up the TOC editor. The TOC editor is very easy to use.

Once you have finished creating your TOC in the TOC editor click OK and all the necessary changes will automatically be updated and saved in the the content.opf and toc.ncx. Then save your azw3 file to your desktop and you're done. Your azw3 file should now have a doc TOC and Nav TOC when you test it.

I must also add that it is not possible to display a multi-level Nav TOC(device TOC) across all Kindle devices. KF8 yes, mobi7 no. On a mobi7 device your multi-level Nav TOC will display as a flat TOC and there's no cure for this because it's the Kindle reader software(mobi7) that flattens the device TOC.