[stumped]

i have found to my horror that using modify epub plug in on a poor quality source i.e. one where I have done lots of manual splits and edit operations to make it one file with one header tag per chapter --

then the modify plug in puts all the html files into alphabetical order and changes the navigation entries to match, so that chapter order is scrambled.

i think changing my workflow would be easier than trying to debug that process so what can I use instead please
i just need something that checks toc and inserts a cover page, so that when I create a kepub for my kobo, it all works well

this is what modify does to chapter order : for a simple made up example

if book consists of 3 files , and the 2nd one was created as a manual split e.g.
html 1
split point 1a
html 2

with matching chapter sequence 1 , 1a, 2

then after modify epub, that becomes
html1
html2
split point 1a
and nav becomes 1, 2, 1a

i stress, its fine with most books, it only goes haywire when there's an underlying mess of file names due to manual edits and splits . i see no way to stop the plug in from doing this alpha sort and subsequent reordering. ( I'd probably be better familiarising myself with recent calibre edit tools and not using this ( quite old) plug in when fixing chapter structures