
LuisG.20493 (Customer) asked a question.
I want to populate a custom attribute on the OKTA user profile with an "alternate userID", but not for all users.
I want the custom application username format expression that will use the "alternate userID" if not null, but move on to use the "samAccountName" if null.

Hi Luis,
You cannot have Okta User profile attribute for few users. it's like for all or for none. But you can have null value for that custom attribute "alternate userID" for few users and other users can have value derived from expression or static value based on your requirement.
I didn't understand your second question completely so cannot comment on that. are you looking for an expression ? you can learn Okta's Expression Language by visiting https://developer.okta.com/docs/reference/okta-expression-language/