You cannot add her W-2 to your own tax return.
She does not have to file her own tax return because she made less than $15,750. However, she should file a Form 1040 if her employer took taxes out of her paycheck. Filing is the only way for her to get that money back as a refund.
You can still claim her as a dependent on your taxes. If she does file her own return, she must check the box that says "Someone can claim you as a dependent."
Here's some information you may find helpful: At What Income Does a Minor Have to File an Income Tax Return?
