If I leave a will, live six more years and give most of it away, can my heirs go after it all?

If I leave my house to my daughter, some land to my son and a car to a granddaughter and then a few years later give my son most of my money, buy the granddaughter a new car and give the old one to the other granddaughter, and all my personal affects to friends and relatives before I die--can my daughter go after all the items I gave away?