Generally speaking, a wrongful death lawsuit is brought by or on behalf of those persons who survived the child after his or her death from child abuse. (See California Civil Procedure section 377.60(a)) In the case of a child, the most important law defines who can bring a wrongful death case - and it is likely, but not necessarily, to be the parents. If the parents, or a parent, are deceased, the person(s) (surviving parent, sibling, grandparent) who may hold the right to bring the California wrongful death case would be the survivors who had the right to inherit the child's property had he/she not had a will - which no child likely would have.
The law states that persons "who would be entitled to the property of teh decedent by intestate (e.g. did not leave a will) have the right (e.g standing) under the California wrongful death statute.
Also, the executor or administrator of a deceased abused child's estate may bring a wrongful death action on behalf of the decedent's eligible heirs. So, in the case of a deceased child whose parents also are dead, but who is survivied by other siblings, a court may appoint an executor/administrator of the deceased child's estate - and that person can bring a wrongful death claim on behalf of surviving brother or sister who lost his or her sibling in California from child abuse.