My cousin Julia Dent married him. She, BTW, was the one who brought the slaves to the marriage. She was something like 3rd cousin to my great grandmother - her father moved to Missouri I think - we are the Maryland Dents not the Georgia coast Dents (although they are all from Maryland if you go back far enough.)
I am not certain, but I believe it is from her line. My Great-Great-Great Grandmother was a Rainey, and was related somehow. I remember my Great-Grandmother telling me that her Grandmother had never told her spouse, as he was a Confederate Soldier, and hated Grant with a passion :)