This similar to what I experienced.

I provided a bank statement (last 3 months) to show that there’s enough funds and the ADB is greater than 500,000 THB. This is a different savings account from where I receive my income for my remote work.

Then came a request for document, a cover letter how i get my income and proof of the income flow for last 3 months.

So I would say if you want to be thorough, to do what you just suggested. A cover letter describing each section of the combined pdfs would help