The 1876 Atlas shows that Sisera Threlkeld owns the nearest blm grant to Hiram M (his father, remember Sisera was the youngest son). The property in question is in Section 32 and Section 29, township 48 range 9, clearly labeled. What I find interesting is the railroad bisected it and there was/is a bridge across Richland creek. I marked it with blue dot on this modern map. The railroad bed is able to be made out going north and the split shown on the Atlas at Callaway Station is visible. Google maps still indicate the RR with a light grey line on map view but the line is clearly abandoned.

http://www.historicmapworks.com/Map/US/480708/Township+48+North+Range+9+West/Callaway+County+1876/Missouri/https://www.randymajors.com/p/township-range-on-google-maps.html?x=-91.95187&y=38.90572&zoom=13

This property is just South of Richland Baptist Church where a number of the Threlkelds are interred including Hiram M.

This property is IMHO the original homestead. Its the oldest grants going back to 1836. The atlas shows 2 buildings on it. This property is listed as East Fulton Township today and John Leland's address on the 1860 census was Millersburg, Bourbon Twsp so I don't think John L was living here at the time.

So I guess I would state that the Threlkeld's lived in the neighborhood of the Givens, not neighbors per se but close enough NW of Fulton that modern Rt HH runs by both farms.

Nancy (Hiram's wife ) bought several blm grants in the 1850's after Hiram's death in 1845. These are on the Callaway Audrain County line which appears to be where Marcellus landed. The bulk of the property was in Audrain County but all parcels are contiguous.