Cassie, Well the names of Dick, Neil, Bonie, & Lonnie unfortunately are not helpful.All Prettyman's originated from Delaware and drifted elsewhere and I don't have any that got up to South Dakota. A multitued of other states though. Also what year was your grandfather born. I can maybe narrow down the search.
The George's that I do have that are unattached or burial unknown are: George W. 1828-?m/ Nancy Spanglerm/Ohio George W. 1874-? m/?b. West Virginia George W. 1849-1894 m/Emma Blackb.Delaware George W. 1883-aft 1900 m/?b. Philadelphia
George m/ Mary C.m/Ohiono dates George1891-?m/?b. PA