How to calculate Household Size I -864

[sys_sagar]

I have a very stratighforward questions:

I live in England and my wife(usc) filed a petition I-130 for me that was formally approved . Now we are in process to file immigrant visa for me(beneficiary). we have a daughter who is also USC.

We need to support the application with Affidavit of Support (form i-864 which is same as used for adjustmant of status in US -i-485)
I have asked my sister in law to sponser me .

Q1. Does my sister in law has to fill in I-864 or I-864A. My wife never lived with them. And I think she will go for Joint Sponsor route
Q2. What will be the household size in her form. She doesnt have any dependant , neither she ever sponsered anybody
Q3. The household size in the form that my wife filled up is 3 including herself as a primary petitioner, myself and our daugher. But she is not working at this moment ans she is in london. So,her income is zero. So, does my sister in law does need to show income to support household size of 4 or just 2\

thanks

[immihelp]

Look at https://https://www.immihelp.comhttps://www.immihelp.com/affidavit-of-support/ to understand how to calculate the household size.