My Brick Wall: Sarah Elisabeth Tharpe McGehee

Hi all -  my brick wall is:

Sarah Elisabeth Tharpe

b.  unknown in possibly Arkansas

d. approx 1900 in Indian Territory now Carter County, OK

buried:  possibly in Oil Springs Cemetery, Carter County, Oklahoma

m.  Alexander McGehee  4 March 1867 in Grayson County, Texas

The only proven information above is that she married Alexander McGehee.  From the time they are married until her death, they are not on any census record I have found.  I know where their children were born:

Siddie Rhuehamie McGehee Caton

     b. 2 Feb 1870, Grayson County, Texas

Haram Marion McGehee

     b. 15 July 1873 in Indian Territory, Oklahoma

John W McGehee

     b. 21 June 1874 in Texas

Mary Elizabeth McGehee

     b. 18 Nov 1875 in Burnet County, Texas

Dottis McGehee

    b.  29 Jan 1881 in Thackerville, Love County, Oklahoma - Indian Territory

James Preston McGehee

    b.  7 May 1883inGainesville, Cook Co., TX

Minnie Mae McGehee

    b.  24 APR 1888inErath Co. Texas

That is all I know about Sarah. I know it is alot more than some know about their ancestors but it is frustrating that once Alexander & Sarah married they do not appear on any census that I can find.  I can find Alexander before he married Sarah and I can find him after her death.

I have searched through census after census and every other document there is to search through. I have been to the cemetery where she is supposedly buried and there is only a partial blank headstone.  I have hers and Alexander's marriage cert but it doesn't provide any info other than they were married.

I know that Alexander lived in Arkansas as a child prior to moving to Texas and that his Dismounted Calvary Unit was in Arkansas during his time as a Confederate Soldier during the Civil War. There is nothing on his pension records about Sarah, the only reference is that he is widowed.

I am at a loss as to where I should search now.  Any tips would be greatly appreciated.