upload

I have a document that is newly uploaded and created on the fly. What is the best way to place the signature fields within the PDF? Is this a separate REST API call?

I would like to have 2 signers. The first one is required to upload an attachment. However, I do not want signing to move to the second signer until after the upload takes place. I would then like the second signer to be able to view the attachment and approve it by signing. Has anyone manipulated a signing session in this format using the API?