The expression to fill the seat of his father occurs twice in the Book of Mormon (Alma 50:40; 3 Nephi 6:19). The expression is not biblical and never occurs in the Bible. It seems to be a Mesoamerican expression. As John Sorenson points out:
Epigraphers who have studied lowland Maya inscriptions have identified a glyph that reads as “CHUM-wan (locative)” and means “seated.” Kaplan believes that this manner of representation first occurred at Kaminaljuyu about 150 BC and was transferred to the Maya lowlands not long afterward. So it is of interest to learn that both Pahoran (Alma 50:40) and Lachoneus (3 Nephi 6:19), each a Nephite chief judge (ruler) in his day, “did fill the seat of his father.” Noah, a Zeniffite (i.e., Nephite) king, sat on a throne at an earlier date (Mosiah 11:9), as did later Nephite judges (Alma 60:7, 11, 21).
(John L. Sorenson, Mormon’s Codex [Salt Lake City: Deseret Book, 2013], 371.)