South Carolina law was amended last year to require all private adoptions of children being placed in South Carolina to be initiated and finalized in South Carolina. I affectionately call it the "South Carolina Rule." The law is explained in this blog post.
Section 63-9-1110(5) of the South Carolina Code of Laws outlines the the family exception to the rule:
Any person may adopt his spouse’s child, and any person may adopt a child to whom he is related by blood or marriage. In the adoption of these children:…upon good cause shown, the court may waive the requirement, pursuant to Section 63-9-60 (A)(2), that the adoption proceeding must be finalized in this State.