Segmentation basis and segmentation Usage

Hi Experts,

In our project we are using a combination of segmentation usage and segmentation basis for authorization purpose. We are doing this authorizations based on sales org structure. Segmentation usage for campaign execution would be controlled through authorization objects CRM_SEGTYP & CRM_STYPE and we have marked"SB mandatory" for this usage type.

Even after making SB mandatory an user will have the list of all Segmentation basis in the drop down list. so I have these questions :

1. What is the best way to control SB at UI level in my case? any mechanism to control SBs or hide the SBs which are unrelated to taht user.
2. What is the best way to create segmentation basis in this case? is it like creating target group for each sales org and then creating Segmentation basis from those TGs?

Please reply if you have any idea about these issues.

Regards,

Sunil