Upload Return Label with Rest or Graph API

[Prince4dev]

Hello,

I was trying to initiate the return from the admin side, and after this I'm developing one app where it can be generating the return label from the courier API, and I just want to update the return label and update the customer with the Rest or graph API.

Can you please guide me on how I can proceed? Until now, what I'm getting is that there will be the fulfillment ID, and I have to upload the return label, something like this. 

In my case:
-- Return already created from admin side without label upload.
-- After that, want to upload the return label through the API. (Only this part I need help)
-- Admin can after that process and finalize the return manually too.

Regards,
Prince