Hi Genegirl, I cannot trace my Pollock line to the middle ages--impressive that you could trace yours so far--but all of us Pollocks are descended from Robert Pollock who took that name in the 12th century. That would be 26,000 of us and counting.
I found more recently that Robert Pollock married Isabel Croce, the daughter of Sir Robert Croce, a knight and peer who lived next door to Robert Pollock, and his wife Eschyna de Molle. Eschyna was married secondly to Walter Fitzallen, the first High Steward. So Isabel Croce is half-sister to the second High Steward.
I just found out this week from a genealogist interested in the families of that period that Eschyna married as her third husband Henry de Molle (a cousin or someone who took her name because she was an heiress), and their daughter Avicia married Richard Scott. The Scott/Douglass line produced many years later Princess Alice who married in the 20th century Prince Henry, Duke of Gloucestor, and Alice and Henry had a son William whom we all are familiar with as an interesting personality. Thus Eschyna was a foremother to more than three notable families.
I am not so interested in demonstrating a direct line as learning of the history of these families in the high Middle Ages, and their interaction, which is fascinating, with pictures on the web which show their life, such as the rolling hills of de Molle by the River Tweed, and the stone Crookston castle of the 14th century which reproduced Sir Robert Croce's wooden castle of the 12th century, which was owned in the 14th century by the Darnley family, which produced Mary Stuart's husband.