Free text invoice report extension

We have a requirement to extend the standard free text invoice report which uses a single design.our request is to create 2 designs for credit note and customer free text proforma invoice.

Dp classes and logic completed. Please some one help me to guide the print management setup and to call the report based on the condition invoiceamount <0 for credit note and before posting it should run the proforma design.
It is required to map in print management form under free text invoice>Invoice & Credit
Also need help on to modify which classes?

Since the std design used every where in the logic there’s a slight confusion.Need your expertise advice.

Hi Experts,
Need your suggestions on this topic.I should choose original or copy preview options to view my designs.