I have written some history on Ector's Brigade; I do not know if this is in time to help you, but I am familiar with the Hartt's (James A. & William J.) of Company C, 14th Texas Cavalry.
I would like to help you in whatever way I can, and in the event you haven't done the marker yet, I would be glad to assist you in whatever way possible.
I am a member of SCV #129 here in Waco; please let me know, if there's anything else you need.