Please review these notes.
Invoice Approval Workflow Current Issues (Doc ID 305704.1)
Invoice Approval Workflow FAQ (Doc ID 305702.1)
Invoice Approval Workflow One-Off Patches (Doc ID 305707.1)
A Guide to Invoice Approval Workflow - setup and demo (Doc ID 299618.1)
APINV - How Do I Setup AP to Use Invoice Approval Workflow? (Doc ID 315269.1)
I looked at the above notes, but I understood that AME needs to be setup if we want to use AP Invoice Approval Workflow....
Does it means can't we customize AP Invoice Approval Workflow to route the invoice as per approval matrix.. The approval matrix we are defining with the help of custom form in custom table.
You can customize the seeded AP Invoice Approval Workflow to pretty much do what your business requirements are.
Many sites do this.
I think it would be easier to use AME group approvals against your custom tables than customize the workflow to the extent you are talking. Basically you will need to go into the oracle package AP_WORKFLOW_PKG and get the code where it is updating the ap_invoices and ap_invoices_lines to set the wfapproval_status to show approved and put that in a custom package which you call form workflow. I think you would also want to update the history table by calling ap_workflow_pkg.insert_history_table.