i read once that when you make a reservation that goes from one season into another , cheap into more expensive, all your stay is calculated at the lesser point cost per day. is this so?
That does not apply to DVC and the point system. You always pay the points for any particular night called for in the point chart regardless of when you begin the vacation. You are thinking of Disney's regular policy applicable to renting resort rooms at WDW through its Central Reservation System.