The child's Social Security benefits reported on a SSA-1099 should have the child's Social Security number in box 2 of the form. The child's SS benefits are not reported on the parent's tax return. If the child has no other income they do not have to file a tax return for the benefits received.
You can claim the step-children as dependents on your tax return just like if they were your biological children. The Child Tax Credit, EITC , Child and Dependent Care Credit are available if you and the children are eligible.
