Who are you trying to claim; your friend or her child or both? Do they live you? If so, did your friend live with you all year and did the baby live with you the whole time since being born?
To claim an unrelated person, they must have lived with you all year (or since birth).
There are two types of dependents, "Qualifying Children"(QC) and standard ("Qualifying Relative" in IRS parlance even though they don't have to actually be related). There is no income limit for a QC but there is an age limit, a relationship test and a residence test. Only a QC qualifies a taxpayer for the Earned Income Credit and the Child Tax Credit.
Neither of them can be your QC, since they re not related. That is, the child may qualify as a dependent, but because he is not related, he cannot be a qualifying child for the earned income credit, child tax credit or Head of Household filing status.
A person can still be a Qualifying relative dependent, if not a Qualifying Child, if he meets the 6 tests for claiming a dependent:
1. Closely Related OR live with the taxpayer ALL year
2. His/her gross taxable income for the year must be less than $4,050 (2016-17)
3. The taxpayer must have provided more than 1/2 his support
4. He must be a US citizen or resident of the US, Canada or Mexico
5. He must not file a joint return with his spouse or be claiming a dependent of his own
6. He must not be the qualifying child of another taxpayer
He must have a US social security number or tax identification number (TIN)
In addition to the above requirements, to claim your friend's children, they must meet all of the above requirements and:
--- your friend must not be required to file a return,
--- she does not file a return claiming the children
