Not sure that I can help much but here is what I have found. First it should be John Marion Allen (from the death certificate). The death certificate that I have says his father's name was W.W. Allen and his mother was Fannie Allen. That information was provided by Eda on his death certificate and therefore she may not have known his parent's given names. I did however find a 1900 census for San Saba county that had his mother as nancy with john m. allen and his brother james c. as stepsons of james Maxwell (after w.w. allen died she married James Maxwell). I am stuck there. They both were stated to be born in kentucky but lived? in Arkansas where John Marion was born according to Eda's information. Not sure where else to look but when I find something I'll post back.