Unsynchronize date between move and line
The line has a function field with a setter for the date which duplicate the date of the move. The problem is that if lines already exists and the date on the move is changed, the client may try to save a date for the move and another for the line. This may create conflict with the period or have an unpredictable behavior for the user (if the dates are both compatible with the period) as the date of the last line will be actually stored.