According to my genealogy program I am a half first cousin 3 times removed to John, David, Philip and George (and the 8 other siblings, including your great grandmother Catherine!)
My line goes to Christopher E Ruckle's father, Philip, but down from his second wife Elizabeth Ashbury, not Mary Dolmage.
The Ohio State library has copies of the Official Roster of the Soldiers of the State of Ohio in the War of the Rebellion 1861-1866
I received photocopies of extracts from the Official Roster from another relative (Ruth Hibberd nee Moffitt) that provide the following details for Henry, David, Philip and John.Grave information is included for John (which you have) and for Philip.
I don't have any "original" info on George.Where did Nancy get her information on George?
Is John's grave reference correct?
Vol IIpage 448 (Fourteen Regiment, Company I) lists:
Henry C RuckleRank: Private, Age: 19, Entered Service: 12 January 1864, Period of service: 3 years,Remarks: Mustered out with Company July 11 1865 by order of the War Department
David Ruckle Rank: Private, Age: 20, Entered Service: 5 September 1861, Period of service: 3 years,Remarks: Killed in battle of Keneshaw Mountain Ga June 27, 1864
At page 751:
Under 14th Regiment Ohio Volunteer Infantry
David Ruckle, Co[ompany] IRank: Private, Died:June 27, 1864Buried: Marietta, Ga, Remarks: Killed in the general assault on Keneshaw Mountain, Ga
Vol V page 278 (Sixtieth Regiment, Company E)
Philip Ruckle Rank: Sergeant, Age: 26, Entered Service: 30 March 1864, Period of service: 3 years,Remarks: Killed June 17, 1864 in action before Petersberg, Va
At page 749
Philip Ruckle, Co[ompany] ERank: Sergeant, Died:June 27, 1864Buried: Petersberg, Va, Remarks: Killed in action; interred in Poplar Grove Cemetery.
Vol VII page 431 (On Hundredth Regiment, Company F)
John RuckleRank: Private, Age: 18, Entered Service: 7 August 1862, Period of service: 3 years,Remarks: Killed Aug 6, 1864 in battle of Utoy Creek, Georgia.
At page 754
John Ruckle, Co[ompany] FRank: Private, Died: Aug 6, 1864Buried: Marietta, GA, Remarks: Killed in the battle of Utoy Creek GA,Interred in section F, grave 887