Greg, I don't really know the parents of John Cromer but I suspect we are on the right track. The LDS site shows that John Cromer married Mary Elizabeth Whitman 20 Sept. 1844 in Richland Co.OH.Since you mentioned the Whitaker name, and the LSD site shows Whitman, it may be a transcription error, but still the same person.
You have given the parents as David and Rachael Sellers Cromer as possibly being John's parents. Do you have more info on them? Do you know if they had daughters named Mary and Margaret? What co. in PA were they from?Was Rachael from MD or VA?I would be delighted to have more on them as I have searched for a long time. Thanks.