Option to upload additional documents

[pbu]

Hi Folks, I am asked to submit several additional documents for my work permit application. But in Check status and messages > View submitted application > Supporting Documents there is only one slot saying as Letter of Explanation as document name and details as "Replacement Needed". So should I combine my additional documents to a single pdf and upload to this slot? If then do I need to include any letter of explanation as to the first page?

Thanks,