You're right, but we don't have a joint sponsor. From what I understand based on the instructions for Form I-864, my mom, as the petitioner, will complete the I-864, and my sister, as a household member, will fill out the I-864A. In this case, their finances will be combined, including my mom's assets and my sister's income. But I could be wrong, so I appreciate any clarification on this. I’m very stressed about that and would be so grateful for your help!