Here is the article about how to set this up.
Resolution for 'Combine separate issue: 'Combine separate bank feeds into one account?' available: Yes.
The Combine separate 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 Combine separate issue yourself by looking for a resolution described in the article. If it is a complex Combine separate issue or you are unable to solve the issue, you may contact us by clicking here or by using other Combine separate support options.
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