Hi Aden,
If I understand you well, you want to choose correct index based on current user role? If that is the case, you can use this piece of code to check if current user is in specific role:
MembershipContext.AuthenticatedUser.IsInRole("YourRoleName", SiteContext.CurrentSiteName)
I think that this, in combination with simple if-else statement will be enough to solve your problem.