Children of John Demarquis/Demarcus b.c.1825 TN

Looking for information on the parents of and death of John Demarquis/Demarcus b.c.1825 TN who married a Melinda/Malinda McElmurry or Freeman.They had two children Mary E born about 1849 in Cook Co, TX and Nancy J born 1852 also in Cook Co, TX.In 1856 Melinda is living in Carter Co, MO and has the first of four children by a Benjamin Franklin Wheeler.Nancy J Demarcus married James Monroe Mills and died in 1883.The fate of Mary E Demarcus is unknown.She is not found after the 1870 census.Does any of this information sound familiar to any Demarcus researchers?