Personalization webpart

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Hi,

I need to develop a web-application, which use form based authentication. In
this application, administrator can create a role and add users to the role.

I have a requirement where the administrator should able to change the
layout of each role in the application. For example, the administrator needs
to add a webpart for the role "External". All users belong to the role
"External" should get the role level personalization .

I know that, personalization can be either user level or shared level but I
don’t know about group level. Can anyone advice how to handle this
requirement?

Thanks,
Shan