Help w/ Python script to generate professional invoice pdfs with reportlab and save

I have the majority of python code already completed -- what it currently does is retrieves data via API and stores the data as 2 lists in the python script. I have the output going to a blank pdf for 1 of the lists (using reportlab). What I need help with is
finalizing the Python code and formatting & combining 2 pdfs.
The are 2 sets of data that are being retrieved from the API -- each with their own invoice - but when there is 1 company that has an invoice for each, they need to be combined.
Cleaning up the output pdf's - general formatting and insert a header image & page numbers
save the pdfs to a folder structure.