Ability to add message before student logs in

[mdhuse]

I set the interactive login message (Local Security) to created a message that displays before the student logs in stating that if they login to the laptop they are agreeing to the laptop agreement that was issued with the laptop. Sometimes the laptop agreement does not get signed and returned to me . This way if they login they have agreed to it. But when the laptop is credentialed that setting is erased. Can there be a way to set that in a config file or that setting not be over written when credentialed?