(a) If notice is required under this Part, it may be waived in open court by the person entitled to receive it or by an agent authorized by that person; it may also be waived at any time in a writing signed by the person entitled to receive the notice.
(b) A person who has executed a consent or relinquishment or otherwise waived notice is not a necessary party and, except as provided in subsection (c) of this section, is not entitled to appear in any subsequent proceeding related to the petition.
(c) A parent who has executed a consent or relinquishment may appear in the adoption proceeding for the limited purpose of moving to set aside the consent or relinquishment on the grounds that it was obtained by fraud or duress. (1949, c. 300; 1957, c. 778, s. 5; 1969, c. 911, s. 6; 1971, c. 1093, s. 13; 1973, c. 1354, s. 5; 1983, c. 30; c. 454, ss. 2, 6; 1995, c. 457, s. 2.)