ESS and R3 users

Hi. all guru's

we are newly iplimented ESS.we are on ECC6,EP 7.0.I would like to know in security. we have ESS user,R3 user.we have two buttons in Ep when both are longging.But we need to place both buttons on the screen,when the ESS user logons to the screen R3 tab to be Disable.when R3 user logon both the buttons are to disply.we have 3000 ESS users and 700 R3 users.what will be the solution to sart out the problem.

Thanks

malee