Isaiah 8:18 (King James Bible) behold I and the children whom the LORD hath given me are for signs and for wonders in Israel
Initially, the 1852 LDS edition dropped the relative pronoun whom, probably because whom serves as the direct object and is therefore optional (“the children the Lord hath given me are for signs and for wonders”). The second printing of the 1852 edition supplied the missing whom, perhaps by reference to the 1840 edition.
Summary: Maintain in 2 Nephi 18:18 the object relative pronoun whom (the King James reading).