You can add that person as a user on that company file, paulg123.
QuickBooks Online has four user types. These are:
The first two user types count towards your user limit while the remaining two don't.
To add a user in one of your companies, please follow these steps:
Once that user receives the email invite, all they need to do is accept it so they can access the company file.
I'll be around if you have any additional questions.