Found on the 1850 Henderson Co. KY census: Rev. Wm. G. Allen (Presbyterian) his wife Ann 24, John N. 5, Mary L. 2 months taken in Jul, all born in KY, Sarah Snyder 12 (birth place undreadable Ancestry.com has IA).
I know that said Wm. G. Allen married 30 Apr 1844 in Henderson Co. KY to Ann Green. Might have married twice again or additional Wm. G. Allen living in Bourbon Co. KY.
I can't find him in 1860 KY census (area around Union Co. KY) & three IN counties other side of the river.
He married my Sarah E. Snyder to George G. Hopgood in Union Co. KY 2 Jul 1862.
Because of the above information I believe Sarah's parents died in Henderson Co. KY before 1850.
If others know how and when Rev. Wm. G. Allen took in said Sarah Snyder, would think to hear from you.