At the end of my interview, I was told I needed a joint sponsor, (I had written a post on this, which has subsequently vanished).
Ultimately, I was able to secure a joint sponsor and have a copy of their signed and dated I-864, Bio page of U.S. Passport, W2 together with 1040 Tax Return for the most recent tax year. This required information came from the double-sided green form that was handed to me at the end of the interview. The form went on to say that I will receive an email in 1 to 2 days after my interview with instruction on how to send these documents. The email is the same as what’s noted on https://ais.usvisa-info.com/en-gb/iv and has received emails in the past, (courier and appointment confirmations). I have not received any email though in the 1 to 2 days as indicated.
Looking at CEAC, there is no option to upload documents for any other sponsor/joint sponsor, as only the primary sponsor is named.
There is an email address on the green form, unsure if I should upload the documents there? Would very much appreciate any guidance, perhaps someone else has experienced this? Thank you.