Each subscription corresponds to one company file, so adding a second one to your QBO account is unavailable, baisyoltruck.
You'll need to sign up for a new QuickBooks account for the second company and register using the same sign-in info as your existing one. This way, you can access them under one Intuit account. Follow these steps:
Feel free to post again if you have further questions about the second account or navigating within QuickBooks. I’ll be here to ensure a smooth and efficient use of the platform.