Thanks for reaching out to the Community, @Rudolf.
To start off, make sure that they are already added or set up as clients in your QuickBooks Online Accountant (QBOA). Here's how:
1. Go to Clients menu at the left under Your Practice.
![53.PNG 53.PNG](https://quickbooks.intuit.com/learn-support/image/serverpage/image-id/18381i451D7880A9ACAC05/image-size/large?v=v2&px=999)
2. Click Add client and pick whether the client is a Business or Individual.
3. Enter the necessary information, then under QuickBooks subscription, select whether you or the client will pay for the subscription.
4. Choose Compare, then pick a product.
5. An email will be sent to your client so they can set up a user account.
6. Hit Save.
Once done, here's how to add them to your Wholesale Billing account:
1. Go to the Gear icon at the upper right, then pick Your Account under Your Company column.
![54.PNG 54.PNG](https://quickbooks.intuit.com/learn-support/image/serverpage/image-id/18382i535C8844E8782481/image-size/large?v=v2&px=999)
2. Click Add existing clients, then check the boxes for the clients to add.
3. Select Add clients.
4. Read the notification, and Continue.
For additional information, check out this article: Add or remove clients from Wholesale Billing.
That should do it. Please let me know how it goes or if you need anything else. I'll be here to help. Have a great rest of the week.