If the check was reported in the child’s name and social security number then it would be reported on the child’s return only. 

The person who has the legal right to receive the benefits must determine whether the benefits are taxable. 
For example, if you and your child receive benefits, but the check for your child is made out in your name, you must use only your part of the benefits to see whether any benefits are taxable to you. One half of the part that belongs to your child must be added to your child's other income to see whether any of those benefits are taxable to the child.
Generally, children receiving survivor benefits are 18 or less and they have very little if any other income that would make the social security taxable. Therefore survivor benefits are rarely taxable to the children receiving them.