Make it clear to him that in nature balls are a solitary burrowing python that spends all of their time in tightly confined spaces and only interact with other pythons for breeding purposes. Tanks are pretty for us as owners to looks at, since it puts the animal on display, but balls are most comfortable where they can hide away. Cohabiting is a terrible idea with most species of animals. Even cats and dogs encounter problems when you keep more than one together with no safe place for one to retreat to.
It sounds like your dad is thinking more of a breeding colony. Some lizards can be kept like that, but solitary snake species like ball pythons are likely to be too stressed to breed under conditions like that.