请教8老师: Who should sign Form I-864W, petitioner or beneficial/app st.paul2018-01-22 05:08:43

Ms. J' is the self-petitioner of VAWA I-360, which has been approved. Her son, 20 years old, living in China, is about to apply for an immigration visa.  According to the instructions, her son should sign the Form I-864W, am I right? Could Ms. J sign the Form I-864W on behalf of her son?