It is foolish to reserve your existing mobile number for family and select friends only by acquiring a new number and blasting everyone with: "This is my new number. Please disregard my old number." People will NOT disregard your old number; they will keep it as a backstop, and they will sometimes dial it out of habit, thus depriving you of the privacy you were expecting.

If you want a private number for family and select friends only, use the NEW number for that, and give the number to no one else but the people you want to call you via that.