InfoPath Dev

Unfortunately 2 of the 3 people change all the time depending on which department or department head has to access the form.  I'm trying to add a username field, then another field will concat the username with ending email to match to the requestors email.  Then I set the field to if those 2 fields aren't equal it doesn't ...

I have a web enabled form where one field needs to be visible only to the originator, the authorization signoff, and HR.  I'm trying to figure out the best way to do this.  I figure I can do a rule where the field is hidden but can't figure out which/what to setup the rule.  Basically is user A, Mark, is the requester then ...