"I think that is very iffy. A tradition emerged in heraldry where people assumed they were related to another family of the same surname and adopted similar but not quite the same arms. You need to be careful here."
I'm not sure that that was a common practice at any stage and certainly not a "tradition". In any case we are specifically discussing the 12th/13th century period when surnames were almost unknown and, as I said, most of the Normans and Norman /English would have known each other's families. They would also have met at tournaments and on the battlefield, so an imposter would have difficulty in staying undetected.
You'll note that I did say "on the balance of probabilities" referring to this period. I would not give the same advice for any time a century or more later.
Maec
