Hi @waqas_ahmed,
If you’re not sure which SSRS report is printed in F&O, you could turn on the flag “Discover report technical name” under User options. Then check the info box when printing to see which SSRS report is being used.
More info in this forum post: Discover report technical name
The Pro forma invoice is basically the same as the Sales invoice. The only difference is the document name. When you print a Pro forma invoice, D365FO still uses the SalesInvoice.Report. That’s why you won’t see a separate report called “Pro forma Invoice” in the replica report list.
Hope this helps!