post https://gateway.stage.bill.com/connect/v3/network/invitation/customer/
Send an invitation to connect a customer created in your organization with a customer in the network. BILL sends an invitation email to the customer email address.
When the customer accepts the invitation, the customer in your organization is connected with the invited customer. If the invited customer does not respond, delete the invitation (with DELETE /v3/network/invitation/customer/{customerId}) before sending a new invitation.
Note: If the invited customer does not respond to an invitation for 60 days, the invitation expires.
See BILL network in the Guides section for more information, sample requests, and responses.