The Isaac Collier who married Elizabeth Cresap did not migrate to Shelby Co., KY.
Tax records in Shelby Co., KY from 1802 to 1815 consistently show this Isaac Collier's son Michael Collier in Shelby Co., KY. with significantly more assets than the Isaac Collier listed adjacent to him. That Isaac Collier starts out being listed as over 21, but without any assets. Michael Collier's son Isaac Collier was born in 1780, so the Isaac Collier listed has to be the grandson of the Isaac and Elizabeth (Cresap) Collier in this profile.
As only Michael Collier (married Elizabeth Parker) who migrated to Shelby Co., KY and his sons appear in the Shelby Co., KY. tax lists, did Elizabeth (Cresap) Collier really die in Shelby Co., KY. ?
The most that can be proved is that Isaac and Elizabeth (Cresap) Collier's last proven location was in that portion of Frederick County, MD that became Washington County, MD. in 1776 and in 1789 became Allegany Co., MD.