Ruth,
Hi. Referring to Otto's book, Mary "Polly" Ann was the 6th child of Joseph and Sarah "Sally" (Robinson). Joseph Seabaugh was born in about 1773 in Lancaster Co., PA, although the record is not precise on this. Joseph was one of the sons of Christian, who first settled in SE MO after travelling from PA to NC to MO. I can provide more from the book if you'd like. You can contact me by email.
Craig