Hi, I hope that the following information helps you. I have the previous generations before Joshua if you'd like to have them.
Robert Morris had a brother John who was born between 1818-1827 and married to Margaret. I believe that they also were in the Adams County, Illinois area. Margaret is buried in the Evergreen Cemetery Camp Point, Adams County, Illinois
There was also another brother Isaac b. 12/14/1820 and died 7/22/1892 Adams County, Illinois. He was married to Melinda N. Durbin in 1845 Uniontown, Fayette County, PA
All 3 brothers traveled to Adams County between 1849-1855. Robert Morris went around 1850. His son Anderson was born in 1849 in Uniontown and Lewis was born in Camp Point, Illinois
Excerpts from the book: Alma: Towards the Year 2000; p.200 courtesy of Patti Simpson:
Robert Morris Prettyman was born in Delaware, the son of Joshua & Eliza Owens Prettyman.Joshua started to migrate to Illinois; however, he became ill in Uniontown, Fayette County, PA., and died there. Robert Morris married Mary Hawke of Uniontown, and migrated first to Camp Point, Illinois, and then to Louisa County, Iowa, and finally to Harlan County, Nebraska, where he died Dec. 30, 1891, age 73 years.
His wife Mary also died in Harlan County, Nebraska on July 26, 1894, at age 75 years.Both Robert and Mary are buried in the Alma Cemetery.
IOWA, LOUISA COUNTY 1856 CENSUS -- SORTED INDEX
PrettymanAnderson7 Penn.Columbus City Twp42 PrettymanHelen9 Penn.Columbus City Twp42 PrettymanJohn11 Penn.Columbus City Twp42 PrettymanJoseph2 Penn.Columbus City Twp42 PrettymanLewis5 Penn.Columbus City Twp42 PrettymanM. A.36 Penn.Columbus City Twp42 PrettymanRobert36 DelawareColumbus City Twp42 PrettymanWilliam15 Penn.Columbus City Twp42