The answer to the first question is no, and to the second is yes. However, I would recommend the opposite! A codicil is a short document to which the same rules of execution apply as for wills and which must be attached to your original will setting out the changes. Codicils can create more problems than they address (inadvertently contradicting the terms of the original will, for example) and for that reason are often discouraged by most estate lawyers. For any changes to the gifts you intend to make, I recommend that you simply update your will in its entirety, so that all the terms of your will operate together clearly. Often the price difference is nominal, so it makes sense to ensure your wishes are set out accurately.