security based combo box

All, 

We currently have a combo box (with entities) in a dashboard but we would like to make this list a bit smaller and based on the security rights a users has. 

I want to solve this with a XFBR which i afterwards attach to a parameter and that parameter in a combo box. 

Does somebody has an example of this XFBR code which i can look into? Or is there a better way to do this.

Thanks