Word: update sublist numbering automatically when the parent list changes

I use Word 2019 on Windows machine. I already have created two lists like the following:

1   List item 1
2   List item 2
    2.1 Item
    2.2 Item 
    2.3 Item
3   List item 3
4   List item 4

Now I need to add a top level section above section 2. I copied the first section and pasted. It looks like this:

1   List item 1
2   List item 1
3   List item 2
    2.1 Item
    2.2 Item 
    2.3 Item
4   List item 3
5   List item 4

The number for the original section 2 becomes 3, but the sublist inside it still starts with "2". How can I make them automatically change to 3.1, 3.2, and 3.3 without me doing anything? I guess I need to connect the numbering of the nested list to the parent numbering somehow, but I don't know how to. Thanks.

Solution 1:

You need to associate your numbering with styles through the Define New MultiLevel List Dialog.

See my answer at Importing numbered paragraphs.

That relies on information from Word MVP Shauna Kelly on her page How to create Outline Numbering or Numbered Headings in Word

Essentially, each level in numbering is associated with a separate existing paragraph style. Each associated style is associated with only one multilevel list level.