John and Robert settled in the Brimfield area of Illinois. I did a little checking last night and found on the Reid & Kendrick site that the Esther d/o William and Ann Bridson m Marmaduke Clark so you can eliminate her. My John Bridson was still in Marown on the 1851 census living with his inlaws but was in Illinois by July of 1851 so the timeframe works.