I saw this movie in the mid 90’s, can’t recall if blk/white or color, might be a foreign film, was rented from local video store.  Movie begins with father and two girls (sisters?) traveling down country road.  Girls ask father to stop car, they enter side land (bathroom break?) and while father waits in car, they continue to woods.  He tries to find them but can’t see them even though they are right there.  Girls realize this must be fantasy woods and begin to live life out of their thoughts.  They think a house into existence, friends, even a swimming hole.  Eventually, they return to the car to find their distraught father and continue on their ride.