Immigrant Visa

I’m the applicant for IR5 visa. The petition was approved in 2015. At the time, the petitioning sponsor, my American daughter, provided her tax forms and signed form I-864. We had to find a joint sponsor as the petitioner did not have sufficient income. We submitted form I-864 for the joint sponsor. Later, I was called for an interview at the Consulate and was told to submit the joint sponsor’s wife’s approval as they file taxes jointly. At that point I gave up and never sent what they requested. But in December 2019 the consulate sent me a request to appear for an interview at the end of which I was told that the case will go to administrative processing. To sum up, currently, they’re processing an immigrant visa for me and have requested new documents. I have a new financial sponsor ready. But my daughter, the petitioner has been jobless and homeless for a while. She can’t sign or provide any documents. My question is: Can I submit the petitioner’s I-864 which she signed in 2015, with a letter of explanation?