One groff file outputting multiple pdfs?

[Richard Morse]

Hi! I am using groff to generate some PDF reports. Each report consists of data 
for a number of different invoices, each of which is going to a different 
payee. We are being asked to submit each invoice separately, so we need to 
create a separate PDF for each center.

The roff file is being generated by a program, and for a few reasons, it would 
be much easier to have the program generate one output file, and then run Groff 
on the single file. Is there someway, perhaps using the mysterious “I/O” 
requests, to have the roff file change the output file through out?

Basically, I would like to run:

        groff -ms -Kutf8 -Tpdf invoices_2020_10.ms

And have it generate:

        invoice_2020_10_siteA.pdf
        invoice_2020_10_siteB.pdf
        invoice_2020_10_siteC.pdf
        …

Without having to generate a separate .ms file for each site, and then run 
groff separately for each invoice.

Thanks,
Ricky