1. Create Vendor udf
2. Create AP Invoice Header BO udf
3. Create AP Invoice Header Posting BO udf
4. Create AP Open Invoice BO udf
5. Then Customizer Selection: A/P > Common Entry > DSELECTINVS (add UDF, which will add it to the Invoices Select screen)
6. Then during the invoice selection process, you can sort by that new UDF column and select the applicable invoices.