"Sharing" an app no longer in the app store

[Spideydavef]

hi

Hope someone can help. My son used to play zombie smash on my iPad. He now has one of his own linked to my account and wants to pus the game on it. However as it's no longer in the App Store I can't seem to find a way of doing it. Is it possible to "family" share or share via cloud or other means, or will he have to use my iPad as that's the only place it exists now?

Thanks