If they are billed together and paid together then they are setup as sub accounts under the parent account.
Resolution for 'connect issue: 'Cannot link two credit cards to one QB credit card account.' available: Yes.
The connect 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 connect issue yourself by looking for a resolution described in the article. If it is a complex connect issue or you are unable to solve the issue, you may contact us by clicking here or by using other connect support options.
For more information about resolving issues related to connect in Quickbooks/QBO or to get support for the issue 'Cannot link two credit cards to one QB credit card account.', click the link below: