CR1 question about I864-A form about household member filing jointly with a spouse

[Zarannn]

So I just have a question, my husband is the immigrant/beneficiary, I (his wife) am his main sponsor, my mother is the household member contributing her income (sponsor). My mother is filling out the 864-A form, and I was wondering if my mother (household member) is married and files jointly with my dad, does my dad have to fill out an I-864 A form as well? Even though my mom alone meets the income requirement? Also on the 864-A form, part 4, regarding the total income on tax returns in the past 3 years do I put in the amount both my mom and dad made jointly? Or just my moms income? Thank you so much!