When you're logged into your work account (say, in GMail), does the URL contain /u/0 or /u/1? And how about your personal account?
Whichever one says /u/0 is the first one you logged in as, and that will be the default if you, say, open a new tab and paste in a bare link (without /u/ in it).
If you want that to be your personal account, you can make that your /u/0 account by doing this:
No way am I merging my work accounts, my personal business accounts, and my junk email together. Especially with a company already proven to slap happy deleting accounts they don't like.
Regarding your first sentence: Those instructions don't merge anything. All they do is swap the order of two accounts that someone is using multilogin with.
Regarding your second: Citation needed. There's this persistent rumor that if you make a G+ account with a fake-sounding name, Google will lock you out of your GMail and erase all your Google Docs, but as far as I've seen, those rumors have never checked out.
Whichever one says /u/0 is the first one you logged in as, and that will be the default if you, say, open a new tab and paste in a bare link (without /u/ in it).
If you want that to be your personal account, you can make that your /u/0 account by doing this:
1. Log out of all your Google accounts
2. Log into your personal account
3. Click the picture in the upper-right
4. Click "add account"
5. Log into your work account