Visitor visa online documents upload after application submission

[t1s2010]

I submitted UK visitor visa application for my family member start of July; and for documents upload, application mentioned that I can return to website and upload the documents later. Though, it didn't allow me unless I uploaded "some document aka non-blank page" so I uploaded passport copy to ensure I can pay and book appointment.

Now, when I am logging again to upload other documents payslips, statements etc., I do not see any option to upload document on the website.
I see two options "Download Checklist" and "Provide documents and bio metrics". Provide document option mentions "make arrangements with our commercial partner (of course commercial!!! )".

In short, can I upload the documents without a few or only option is to give in to VFS ransom when attend bio metrics?

[Singh_harv]

Are you using vfs as commercial partner? If you are you will need to login to vfs website and select my application then search using your gwf number then you will get option for document upload