In fact, this question is very simple, but you haven't found the right method yet. Just follow my next steps. For example:

All the above names should be in one line, with,? Separate (it's ok not to separate, but it's better to have some space for beauty).

The first step is to turn on Find and Replace.

The shortcut key is "Ctrl+H", which can quickly open this page.

Step 2, enter "p" in the search content.

This "p" stands for line feed.

Step 3, replace with the input ",". If you don't need spaces, don't write anything.

Step 4, select "Replace All".

Then close the "Find and Replace" page, and you will get the page you want as shown below:

Well, that's it. Just a simple replacement. It's no big deal, but you don't know the line break "p" This problem can be solved in the future.