Yes, a codicil is an option in the sense that it can be used to make the changes you are describing. However, it is not likely to be less expensive than creating a new will. It is usually simpler to create a new will than to make sure that a new codicil is coordinated with a 17-year-old will. The only sure way to answer your question is to call local estate planning lawyers and ask them how much they would charge to create a codicil to modify your old will.