Welcome to the Community, sidirhayw.
Let me address your concern about adding multiple users in QuickBooks Self-Employed (QBSE).
At this time, there is no option to add another person to your self-employed account. However, you can allow your wife to sign in to your QBSE account from her computer. Just make sure that you share the correct login credentials with her. Remember to sign in one at a time to ensure that the transaction recording is entered correctly into the system.
You can also share this article with the other person who currently logs in to your QBSE account. The article provides details on how to manually enter sales income and expenses in QBSE: Manually add transactions in QuickBooks Self-Employed.
Moreover, if you want to learn more about managing multiple companies, check out the following link. It has a lot of useful information that can benefit you and your business: Managing your companies.
Also, if you want to see different details on how QBSE developed to help you record your self-employed income and expenses, track mileage, and prepare your Schedule C, you may refer to this article: QuickBooks Self-Employed Overview.
I'm only a comment away if you have any questions about multiple users or any QuickBooks Self-Employed-related concerns. Take care and enjoy your weekend.
