You want to be using Customer:Job, like this:
“(caterer} is the main customer typed at top invoice.”
That is customer. The “served client” = Add Job to that name. Now you Invoice, top left “Customer:Job” = Caterer:Their Actual Client
“A preferred “caterer” pays us a % of total money charged to the other customer.”
Resolution for 'Christmas Party issue: 'Attach second customer to invoice' available: Yes.
The Christmas Party issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the Christmas Party issue yourself by looking for a resolution described in the article. If it is a complex Christmas Party issue or you are unable to solve the issue, you may contact us by clicking here or by using other Christmas Party support options.
For more information about resolving issues related to Christmas Party in Quickbooks/QBO or to get support for the issue 'Attach second customer to invoice', click the link below: