No. The sole purpose of a model release is to give you rights to use the images. A model release is not a parental consent form although a parent signing a model release inherently means the parents are aware of and consent to the shoot. If there will be no usage, there is no need for a model release to authorize nonexistent usage. Senior portrait photographers don't ask for a model release. The pictures are for sale to the family and that's it. There is no need to hunt down parents of a class of 1,000 for model releases.