The I-864A is filed by the household member such as the sponsor's spouse, not the sponsor. So, you may complete a new I-864A and answer the questions on I-864A correctly, e.g., only put the sponsor's spouse's personal income in the I-864A, not entire family income. Then, provide the support documents such as the copies of the joint taxt return of 2020, W2, and the employment verification letter from the employer.