are the 8 and 11 year olds your qualifying children. they are if the following tests are met. in that case your 19 year old can't claim them (i've omitted tests you've meet or don't apply)
Qualifying child
- Same principal abode as taxpayer (you) for more than ½ the tax year. Temporary absences like for school are ignore
so if they lived with you, you 19 year old doesn't qualify to take them
should they live with your 19 year old, but not you, then he would have to meet these tests (again i've omitted tests he would meet
- your 19 year old provides over ½ their support
and isn’t a qualifying child of another taxpayer. A person is not considered to be the qualifying child of another taxpayer if that other taxpayer is not required to file a tax return and that person (1) does not file such return or (2) does file solely to claim a refund of withheld taxes. This exception doesn’t apply when the other taxpayer files a return to receive the earned income credit
