This is off the top of my head: I have long been suspicious of any of their offerings as being rewritten from Child's published versions. I do believe there are some Smith ballads that are unique to them in American tradition. However they are part of a long and illustrious tradition occurring in all English-speaking countries which almost rivals, at times, the oral tradition.

Apart from this I'm sure I've seen references by other editors of their suspicions of the Smith material.

I would even go back, if I were you, and put riders on all of the Smith brothers' contributions.