Can you do it yourself? I suppose so. I could do brain surgery on myself. But I am not a doctor and don't have a clue what I am doing in the surgical arena. Likewise, you should not draft your own will or codicil as whatever you create may or may not be valid and may end up resulting in a costly lawsuit because you tried to save a few dollars.
If your will was properly drafted, then it would say something to the effect of "in the event my children are minors or under age 18, then I appoint X as guardian." In such case, there would be no need to amend your will at all since the children are no longer minors.
If the will was done properly - i.e., by a competent lawyer, signed by you and 2 witnesses who are not beneficiaries under the will and notarized and otherwise complies with the GA requirements, then the will should be good in SC. Below are some helpful SC statutes:
SECTION 62-2-505. Choice of law as to execution. A written will is valid if executed in compliance with Section 62-2-502 either at the time of execution or at the date of the testator's death or if its execution complies with the law at the time of execution of (1) the place where the will is executed, or (2) the place where the testator is domiciled at the time of execution or at the time of death.
SECTION 62-2-502. Execution. Except as provided for writings within Section 62-2-512 and wills within Section 62-2-505, every will, shall be in writing signed by the testator or in the testator's name by some other person in the testator's presence and by his direction, and shall be signed by at least two persons each of whom witnessed either the signing or the testator's acknowledgment of the signature or of the will.
Its a good idea to periodically review a will to make sure that it is not out of date and still comports with your wishes. Any time there is a major life-changing event like a birth, death, marriage, divorce, adoption or relocation, the will needs to be reviewed by an estate planning attorney in your new state of residence.
In addition to a will, your estate plan should include a financial power of attorney and healthcare directive (this goes by different names in different states - GA combines a healthcare power of attorney and living will into a single document - you either need the combined document or a separate living will and health care power of attorney).
I am not licensed to practice in SC and I am not purporting to advise you of the SC laws. However, in the interest of helping you, I pointed out the parts of the SC law which may be of benefit to you. As I said, you should consult with an attorney in SC.
Since you want to make changes in your document anyway, your best bet is to simply hire an SC attorney to prepare a new Will. That will allow you to make the changes you want and to be sure that the Will takes advantage of SC's law. Wills are not expensive to prepare through a lawyer and the cost is MUCH less than hiring a lawyer to clean up the mess, after you are gone.
***Please be sure to mark if you find the answer "helpful" or a "best" answer. Thank you! I hope this helps. ***************************************** LEGAL DISCLAIMER I am licensed to practice law in the State of Michigan and have offices in Wayne and Ingham Counties. My practice is focused in the areas of estate planning and probate administration. I am ethically required to state that the above answer does not create an attorney/client relationship. These responses should be considered general legal education and are intended to provide general information about the question asked. Frequently, the question does not include important facts that, if known, could significantly change the answer. Information provided on this site should not be used as a substitute for competent legal advice from a licensed attorney that practices in your state. The law changes frequently and varies from state to state. If I refer to your state's laws, you should not rely on what I say; I just did a quick Internet search and found something that looked relevant that I hoped you would find helpful. You should verify and confirm any information provided with an attorney licensed in your state. I hope you our answer helpful!
Wills are relatively inexpensive documents to prepare and I always recommend professional guidance. A poorly drafted will can cause a great amount of misery while a properly prepared will can minimize family tensions. Best of luck to you.
This information is provided as a public service to provide a general answer and should not be relied upon as legal advice.