Managing membership in openshift.io

Apologies if this is documented, but I searched and could not find it.

Does anyone know the process for managing membership from within OpenShift.io? For example, I would like to bring in another developer to my project, but the subscription is in my name.

Is this feature specific to OpenShift dedicated, or is it possible to add a co-developer to a project using openshift.io? If so, how would we find their identity to add as a member to a project. They are not a subscriber to openshift.io and, even if they do subscribe, there is not a way to obtain your identity (or it may not even be created) from manage.openshift.com.

Kind regards,
William