S.C. Code Ann. § 63-15-332: Exclusive, continuing jurisdiction.

(A) Except as otherwise provided in Section 63-15-336, a court of this State which has made a child custody determination consistent with Section 63-15-330 or 63-15-334 has exclusive, continuing jurisdiction over the determination until:

(1) a court of this State determines that neither the child, the child's parents, and any person acting as a parent do not have a significant connection with this State and that substantial evidence is no longer available in this State concerning the child's care, protection, training, and personal relationships; or

(2) a court of this State or a court of another state determines that the child, the child's parents, and any person acting as a parent do not presently reside in this State.

(B) A court of this State which has made a child custody determination and does not have exclusive, continuing jurisdiction under this section may modify that determination only if it has jurisdiction to make an initial determination under Section 63-15-330.