there two approaches I could think of:
- Type the text in a word editor (like MS Word) because the tab key will automatically create the sub-levels you want. InDesign could be linked to this file, get the updates and format the content as you need.
- All in InDesign, I would create Paragraph styles, one per each branch level, associate it with a shortcut (Ctrl+NumKey) for easy application. Each paragraph Style would control the indent (Tab) and numbering style. It gets tricky when a numbering has to resume the numbering but you be able to structure it that way.
Please confirm the version of your OS and InDesign
Thanks for sharing. Remember, styles will allow you to save time with updates/adjustments