Your custom dialog message could be a calculation:
Let ( R = Int ( random * 3 ) ;
Case ( R = 0 ; "Message 1" ;
R = 1 ; "Message 2" ;
R = 3 ; "Message 3
) // let
You can also store your messages in a related table where the match field can be assigned the random value of 0, 1 , 2 ... in order to match to different records with different messages.
That is something I thought would also work. Not sure exactly how though?
"match field can be assigned the random value"
Say you have this relationship:
LayoutTable::MatchField = RandomMessages::MessageID
Set Field [ LayoutTable::MatchField ; Int ( random * 3 ) + 1]
Then enters a random number from 1 to 3 to match to a record with 1, 2 or 3 in the MessageID field.