How to merge archived PDF files in One file?

Technical Folks,

I have archived the billing documents in PDF files with the below function modules.

CALL FUNCTION 'ARCHIV_GET_CONNECTIONS'

CALL FUNCTION 'ARCHIVOBJECT_GET_TABLE'

However, I got one PDF file for each document.

How can I get all the billing documents in one PDF file? or

How can we merge PDF files for different documents in one PDF file?

Thanks.

Regards,

Meer