How can I add a customer under existing project

We've got you covered on how to add a customer to an existing project in QuickBooks Online (QBO, Ala7.

QBO associates a single customer with each project to keep things organized and straightforward. To incorporate a customer into the existing project, we'll need to edit the project and add a new customer to it. Here's how:

1. Go to Projects (Take me there).
2. Find and choose the project you want to change the assigned customer for.
3. Click Edit.
4. Select the new customer from the Customer ▼ dropdown.
5. Press Save.
6. Review the prompt, then hit Assign new customer.

Once done, all past invoices and estimates for the project will be linked to your new customer. Then, you’ll need to send any unpaid invoices or pending estimates to your new customer.

If you need to set up a project for your new customer, just follow the steps below:

1. Go to Projects (Take me there) and choose New project.
2. In the Project name field, enter the project name.
3. Select a customer from the Customer ▼ dropdown.
4. Enter a Start date and End date for the project.
5. Choose a project status from the Project Status ▼ dropdown. 
6. Once done, press Save.

Once done, you can now add both new and existing transactions to the project. To learn more about setting up projects in the program, you can check out this article: Create and manage projects in QuickBooks Online and Accountant. 

Moreover, you can refer to these articles to help you add paid/unpaid invoices to projects and create invoices for project expenses:

• Add existing invoices to projects in QuickBooks Online
• Invoice customers for project expenses in QuickBooks Online

We're ensuring that every issue is being addressed effectively to achieve resolutions. Keep in touch with the Community if there's anything we can assist you with, managing your projects, or any QuickBooks-related concerns. We'll be right here to provide any kind of assistance, Ala7.