How to change the client

Dear Friends ,

we have a portal and the users are maintained in R/3 that means UME is R/3 .

Now when i have to give the access to the users to use ESS applications they are not bale to view ESS role since the portal is mapper to client where the user is not existing.

Say for Eg : i have checked in system administration-> UME configuration-> where i found client :100

but the users are existing in 200 .

Now my query is in order to access the ESS applications the users which are created in CLIENT 200 has to be configured instead of client 100 .

What are all the places i have to change inorder to map the system to client to 200.

Is that correct that i have changed in system administration->UME configuration->ABAP system tab

Thanks in advance