Hi there, @finance-thevudho. I've got the answers you're looking for about adding multiple companies in QuickBooks Online (QBO).

Although you can have as many companies as you'd like under the same QBO account, each company requires an additional subscription. You can access them with the same sign-in info. This lets you quickly switch between companies so you can manage everything more efficiently. 

To add a new company:

1. Go to the QuickBooks pricing page and select the subscription you want.
2. You’ll see a page that asks you to create an Intuit account to buy QuickBooks. Scroll all the way to the bottom. Then, look for the small text that says “Adding a company to an existing account.” Select Sign in next to this. 
   
3. If you're signed in to QuickBooks, you’ll be asked to confirm the account you want to sign in with. If the account displayed is the one you want to use for the new company file, select Continue.
4. When asked, enter the same ID and password you already use for QuickBooks.
5. Fill out all the information about your new company and you’re good to go.

Now that you have multiple companies, you’ll be asked which company you want to open whenever you sign in to QBO. To switch between companies at any time, select the Gear icon and select Switch company. For more info, check out this article: Create or add another company file.

Be sure to let me know if you have concerns while working with QBO, @finance-thevudho. I'm here to lend a helping hand. Have a good one.