You can do this on AO3 by grouping oneshots into either a series, or into one long fic split into individual chapters.
Not sure what you mean here, since it would be easiest to simply organise the oneshots or chapters into one collection on upload, so you can just keep adding them as you like or as you update.
If you mean organising the chapters or oneshots in a series in an all ready uploaded story, than it's actually not possible.
You can only do these things on Dokuga via the stories:
- Add/upload a new story
- Delete a story
- Add a chapter
- Delete a chapter
- Edit the story properties i.e. rating, name, genre etc, summary, state if its complete etc
- Edit the story chapters i.e the actual text
- Move the chapters up and down in terms of organisation and or sequence.
You can't do anything else, as there are no other grouping options for chapters, like there are on AO3 for grouping stories, individually, into a series.
~ Pyre