S.C. Code Ann. § 36-3-605
(a) If a person entitled to enforce an instrument releases the obligation of a principal obligor in whole or in part, and another party to the instrument is a secondary obligor with respect to the obligation of that principal obligor, the following rules apply:
(b) If a person entitled to enforce an instrument grants a principal obligor an extension of the time at which one or more payments are due on the instrument and another party to the instrument is a secondary obligor with respect to the obligation of that principal obligor, the following rules apply:
(c) If a person entitled to enforce an instrument agrees, with or without consideration, to a modification of the obligation of a principal obligor other than a complete or partial release or an extension of the due date and another party to the instrument is a secondary obligor with respect to the obligation of that principal obligor, the following rules apply:
(g) A release or extension preserves a secondary obligor's recourse if the terms of the release or extension provide that: