How do I connect with an existing customer in the QB business network?

I can see the importance of connecting existing customers in QuickBooks Business Network, Tom. 

Currently, the option you're looking for is unavailable. As a workaround, I suggest creating a new customer and merging the existing customer with the newly created account that's connected to QuickBooks Business Network. 

I also encourage you to send feedback to our Product Development Team. We promptly review customer requests and consider them when prioritizing product enhancements. 

Here's how:

1. Sign in to your QuickBooks Online company.
2. Look for the Gear icon in the upper right corner.
3. Enter your comments in the description box.
4. Once done, hit Next.

Additionally, you can always visit our Privacy and Security Center to have more insights into how we keep your data secure.

Lastly, I'm adding this resource for you to be able to learn about the different options for user roles and access permissions in QBO: User roles and access rights in QuickBooks Online.

If you still have further queries, please let me know by dropping some comments below. Stay safe, and have a good one.