Hello Marshall Yawney
Microsoft does not allow past invoices to be reassigned to a different billing account due to compliance and audit requirements. Since you have already moved all resources to the new billing account that uses your Partner Success Core Benefits and deleted the old Pay-As-You-Go account, the only supported option is to request a refund or credit adjustment for the charges incurred under Pay-As-You-Go.
To do this, go to https://partner.microsoft.com/support, select Billing, and include your support ticket ID (2509080040006013), screenshots showing the redeemed Core Benefits, the new billing account, and the old invoices, along with a clear statement requesting a refund or credit adjustment for charges before migration. Microsoft will review and process this on a case-by-case basis, as invoices cannot be moved or reissued under the new billing account.
Thanks,
Suchitra.