Provide integration and access control with modules such as Shared Email, Entity Registration and others

I am trying to come up a generic method for managing Parent/Child relations and keep coming back to thinking that the Subuser module ought to be at the centre of a workable solution.

My feature request is as follows:
Provide a collection of companion modules for the Subuser Module which allow for integration with external modules, including the following.

- Shared Email Module. Where a subuser shares the same email as the parent user. The shared email address would injected into the subuser registration and further email confirmation for subusers would be disabled. Subusers would not be allowed to change their email address, unless allowed by the parent. Ref: https://drupal.org/node/896520

- Entity Registration Module. Where a parent can register only their subusers for registration entities. The emphasis being on access control. Currently the registration module allows any user to register any other user including other peoples subusers. Ref: https://drupal.org/node/1653458

There may well be other modules that could benefit from such an approach. Organic Groups comes to mind.

For my use case I am building primary school websites and need to the facility for young children to have Drupal accounts controlled by parents or administrators. However, I can see that there may be many similar use cases that would benefit such functionality.