Hello, @Capstone-33.

I'm here to share some information about mapping Custom Fields to customer records in QuickBooks Online (QBO).

Mapping custom fields to the customer's email and mobile number is not an option in QBO. The Custom Fields are available in the QuickBooks Fields drop-down and aren't intended for any auto-filled fields. These only allow you to manually enter data when creating the transaction. 

However, you'll have to enter the customer info when creating customer records in QuickBooks to show the details on invoices.
 

1. Go to Get paid & pay and select Customers.
2. Select New customer.
3. In the Display name as field, enter what you want to display for the customer. (this is a required field)
4. Then, review each section and enter any other important customer info.
5. Select Save.

I'm also adding these articles as your guide in tracking salespersons on the sales form.

• How to add custom fields to sales forms and purchase orders
• Import custom form styles for invoices or estimates.

Let me know if there's anything else I can help you with today by commenting below. I'm always around to provide the information that you need in allocating the salesperson.