Here is the link on who qualifies as a qualifying relative for a dependent. All other conditions have been met. The only unsure part is the part about making gross income of $4300 or less. Social security income is more than $4300 a year.
https://apps.irs.gov/app/vita/content/globalmedia/overview_of_the_rules_for_claiming_4012.pdf
Under section 3
The person’s gross income for the year must be less than $4,300. Gross income means all income the person received in the form of money, goods, property and services, that isn’t exempt from tax. Don’t include Social Security benefits unless the person is married filing a separate return and lived with their spouse at any time during the tax year or if 1/2 the Social Security benefits plus their other gross income and tax exempt interest is more than $25,000 ($32,000 if MFJ).
However I’m not clear on the last statement. It says don’t include social security benefits (which I’m assuming is the 1099-SSA) unless they are filing married filing separately and live with the spouse? If they are being claimed as dependents, they should NOT be filing any taxes at all. Not separately, not jointly. So none of the conditions even matter.
