AX 2012 - AX 2012 - X++ : from code, generating Pro-forma from packing slip & printing with specific design

Hello everybody,

I have also checked previous posts and didn't find the right answer, but I may not have searched the right way.
(Best article I found was this one, but applies to AX2009 unfortunatly : https://community.dynamics.com/product/ax/f/33/p/47302/85894.aspx)

Anyway, here is my goal :

1/I want to create a profoma invoice from a packing slip order, or from several

2/I want to use a specific design, let's say SalesInvoice.SI_invoice for printing in file pdf named "packingSlipId.pdf"

3/I want all this to happen when clicking a button located in the PackingSlip Journal Form, which does the 2 previous tasks to all selected PackingSlip Orders. I also don't want any Print Form to prompt on screen when clicking that button, all this should happen automatically.

Here are my problems :

I found many helpful code samples, but all apply to AX2009 only.
(You will find below the best I managed to find)

-I can post my packing slip order using the formLetter.update() method

-I am not able to control any bit of the printing methods.

When I chose my specific design, SalesInvoice.SI_Report in SalesI nvoiceController., it still prints the document using the old design SalesInvoice.Report; even if this design doesn't exist anymore in the AOT ! And when I save my report from screen, it choses the name : SalesInvoice.SI_Report, which drives me crazy...If it prints using SalesInvoice.Report, it should at least save with the name SalesInvoice.Report...

Here is what I do:
In SalesInvoiceController.Main()
formLetterController.parmReportName(PrintMgmtDocType::construct(PrintMgmtDocumentType::SI_SalesOrderInvoice).getDefaultReportFormat());
In PintMngtDocType.getDefaultReportFormat()
        case PrintMgmtDocumentType::SI_SalesOrderInvoice:
            return ssrsReportStr(SalesInvoice, SI_Report);

Please, any help on printing management would be very sooo welcome :(

Here's a very good code sample, for AX2009 :

// Created on 11 Jan 2011 by Jovan Bulajic
static void PrintPackingSlipsToPDF(Args _args)
{
    CustPackingSlipJour     custPackingSlipJour;
    SalesFormLetter         packingSlip;
    PrintJobSettings        printSet;
    TransDate               filterDate;
    Filename                pdfFile;
    ;

    // Configure printer/PDF settings
    printSet = new printJobSettings();
    printSet.setTarget(PrintMedium::File);
    printSet.format(PrintFormat::PDF);
    printSet.warnIfFileExists(false);
    printSet.suppressScalingMessage(true);
    printSet.setTarget(PrintMedium::File);

    // Initialize the report
    packingSlip = SalesFormletter::construct(DocumentStatus::PackingSlip, false);

    // Select date of the latest packing slip (e.g. today - to use this for testing)
    select maxOf(DeliveryDate) from custPackingSlipJour;
    filterDate = custPackingSlipJour.DeliveryDate;
    info(strFmt('Printing Packing Slips for %1', filterDate));

    // Process all packing slips for the selected date
    while select *
        from custPackingSlipJour
        where custPackingSlipJour.DeliveryDate == filterDate
    {
        // Set the PDF file name
        pdfFile = strFmt('C:\\Temp\\PackingSlip_%1.pdf', custPackingSlipJour.PackingSlipId);
        printSet.fileName(pdfFile);

        // Print packing slip to PDF
        packingSlip.updatePrinterSettingsFormLetter(printSet.packPrintJobSettings());
        custPackingSlipJour.printJournal(packingSlip);
    }
}