Can I add a secondary phone number for MFA login?

Adding a secondary phone number for multi-factor authentication is very important to secure your QuickBooks Online company, @lwf4. 

I can provide you with some ideas on how to safeguard your account.

We'll send you a one-time confirmation code through your email or mobile device to ensure it's really you that's logging in. I advise entering your husband's mobile number as the primary contact, if applicable, as the ability to add a secondary phone number is currently unavailable in QBO.
 

If not, you may select the option to "Try a different method" and use your email address instead for the MFA. I'll walk you through how to add your email:

1. Login to your QBO company.
2. Click on your profile icon beside Settings ⚙.
3. Go to Manage your Intuit Account to open the Intuit Account Manager.
4. Navigate to the Sign in & security tab.
5. Pick the User ID, Email address, Password, or Phone section.
6. Make your changes/ add your email address.
7. Once done, click on Save.

That should do it! I'll include an additional module that you may find helpful when managing users in QuickBooks:  Add and manage user roles and permissions in QuickBooks Online.

You can always comment back if you need more help with this matter or QuickBooks in particular. We'll make sure to respond as soon as we can. Take the best care!