The beginning place for this family was the Justice book of Dungan geneology:
James C. m. __________ is entry #611, listed as eldest son of Eliza and Hannah CHAMBERS DUNGAN; his children by this marriage are listed as Entries 1570, 1571, and 1572 along with their spouses and children. Serilda is not listed with them.
These entries led to examination of the census records which confirmed the family composition and some Shelby Co MO and CA birth, marriage, and death records.
Finally, descendents of the Thomas Nelson family and the Rachel A.F. DUNGAN sibling lines listed various documentation with LDS and Ancestry.com which led to Serilda's inclusion.
Below are the complete entries I have for them (without the info you have provided for Serilda). Let me know where you have conflicts or my files need to be updated!
6James C. b. 1810 VA, d.bef 1852; m.abt 1834 Ann STINSON b.abt 1816 W VA, d.4/9/1897 Yolo Co CA, moved to NE MO; her m2.2/11/1852 Shelby Co MO James W. ALEXANDER b.1805 KY/TN (his m3.)of Cherokee descent, moved to MO, then migrated Yolo Co, CA (her CHm2: Malinda b.1852 m. John D. WOOD, Daniel J. b.1858)
CH: 7James W. b.abt 8/1835 VA, d.6/7/1911 San Joaquin Co CA, m.1/1/1859 Rachel A.F. DUNGAN d/o James Violet and Sarah GOLLEHON DUNGAN, b.1/11/1839 VA, d.10/25/1897. No children
7Thomas Nelson b.abt 1839 MO, d.3/10/1926 Tulare Co CA, m.10/26/1865 Washington Co VA Joanna MCKEE b.abt 1840 Washington Co Glade Spring VA, moved CA 1894, lived Exeter CA 1917, also listed in census with Thomas W. married Nancy Caroline SMITH below CH: 8Florina b.abt 1866 8Clifford b.abt 1868 8Mack b.abt 1870 8James F. b.abt 1872 VA, d.8/30/1934 Sacramento CA, m. Marian S. UNKNOWN b.abt 1868 MO,d.9/2/1929 Tulare Co, listed in Sacramento Land Records age 17 as DUNIGAN CH: 9Marshall b.abt 1904 CA 9Elizabeth b.abt 1911 CA 8Thomas Nelson Jr./T. M.(in marriage records, this could be Mack above but family documents this line) b.abt 1874 VA (Listed in Sacramento CA land records with James above as Thomas DUIGAN b.1868 IL), m1. 1901 Tulare Ca Sallie SEABRIGHT, m2.Eileen B. UNKNOWN b.abt 1885 CA (marriage 1 in records, m2 only marriage listed by descendents) CH: 9Eugene C. b.12/16/1915 CA, d.2/22/1973 Los Angeles Co CA 9Neil M. b.abt 1917 CA, d.8/1/1958 San Diego Co CA 8Andrew C.M. b abt 1875 VA, d.1/31/1958 Tulare Co CA, m. Ellen T. UNKNOWN b.8/17/1875 CA, d.5/3/192? San Francisco CA CH: All b. CA 9Helen b.abt 1903 m.1921 San Diego CA Henry Wallace MONTAGUE 9Mary Virginia b.abt 1904 9John A. b.abt 1907 8Thomas Lyle b.btw 1887-1907 Exeter Tulare Co CA, d.12/20/1967, m. Lorna E. Raymond (This son is speculative and not listed in all records; could be grandson, but not counted so by descendents) CH: 9Thomas McKee m.Betty FARBUSH CH: 10Cheryle 10Thomas 10Wendy 9Harold 9Donald Eugene 9Beth m. Dick HOLLANDS CH: 10Charles Louis 10Thomas John 10Dorri Lynne 10Susan Lorna 8John Smith b.3/27/1882 VA, d.2/13/1960 Tulare Co CA, m. 1907 Tulare CA Blanche E./K.(in marriage record) JORDAN b./24/1881 TN, d.5/12/1973 Tulare Co CA CH: 9Curtis R. b.3/27/1909 CA, d.3/17/1985 Exeter Tulare Co CA 9Vincent M. b.4/24/1911 CA, d.7/7/1998 Farmersville Tulare Co CA 9John Nelson b.8/21/1918 CA, d.1/29/1976 Exeter Tulare Co CA, m. Katherine LOCEY CH: 10John Smith II resided San Joaquin CA CH: 11John Smith III resides Las Vegas NV 8May G.(in marriage record)/Mary G. b.abt 1879 VA, m.1896 Tulare Ca F.S. MONTGOMERY
7Mary Jane b.abt 1841, m. John M. HAYS/HAYES s/o Henry HAYS Roanoke VA, resided Fort Scott KS