There were several families with the surname McBeath living in Reisk, Kildonan, Scotland circa 1800. James McBeath was married to Ann McBeath, Neil McBeath was married to Catherine McBeath, and John McBeath was married to Jean McBeath. Since the surnames of the husbands and wives were all the same and given how small the population of this area was at that time, it seems likely that these six people were closely related. I don't know whether three brothers married three sisters or whether sons and daughters from one family married sons and daughters from another family. Since James and Ann's second eldest son was named Neil, it seems likely that there was some relationship to the Neil who married Catherine.