QB Issue Resolution:

The bill can not be customized to show additional fields, the MPN can show on the PO

You can, as a work around, put the MPN in the purchase description of the item, but as I said it is a work around

Resolution for Issue 'When I am receiving purchase order against a bill the manufacture part number is not available as a column to show? I need this to ensure correct item received' available: Yes (Solved).
Source: Intuit Community forum.

When I am receiving purchase order against a bill the manufacture part number is not available as a column to show? I need this to ensure correct item received: this 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 issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

Support for additional fields
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