Review copies of your previous wills and other estate planning documents to see what parts you would need to update in addition to including the names of your stepchildren. Review your state's particular requirements for valid wills. FindLaw.com maintains a list of all 50 states' laws regarding wills on its website.
Make a list of all of the possessions and properties that you wish to include in your new will and other estate planning documents.
Discuss your plans for your stepchildren with your spouse who is their biological or adoptive parent. Coordinate the changes in your estate planning documents with your spouse's estate planning documents.
Decide whether you wish to leave your stepchildren property and possessions in your will or whether you wish to provide for them through an annuity, trust or other income stream.
Draft a new will and other estate planning documents, specifically mentioning your stepchildren by name.
Date and sign your will in the presence of witnesses who are over the age of 18, not related to you and who are not mentioned in the will. Consult your state laws for information on how many witnesses you are required to have.
Call your local probate or surrogate court and ask for information about filing your will with it for safekeeping. While your will does not have to be filed with a court until after your death, leaving the original with a court in your lifetime can insure that your wishes are carried out after you die.