Prevent Change to Different Division

We use divisions and sometimes the users will copy a previous sales order and change the customer. The problem comes in that items on the sale order are coded to one division and if the new customer is in the different division  it creates a problem with the GL posting.  They want to know if I can write a script so that if the user attempts to change the customer it has to be in the same division as the current customer. So if the order was originally for a customer in division 10 they can only change it to another customer in division 10, they would not be able to change to a customer in division 30.  Would that be possible? Where is Connex when I need him.