Grouping Rule does not work because Project Billing populates Invoice Number

Goal is to group invoices interfaced from Projects that have the same agreement number.

     Set up Grouping Rule to use optional Line Trx Interface attribute 3 which is for agreements

     Set up Projects Invoices Source to use the Grouping Rule

     Set up Projects Implementation Options to use Projects Invoice Source

When a draft invoice is released in Project Billing a unique Invoice number is assigned.  When several of these draft invoices are interfaced the unique Invoice # is in the AR Interface in the TRX_NUMBER field.  This is one of the mandatory attributes that must be the same for transactions to be grouped into one invoice se we get multiple invoices when we want just one.