The precise identity of the half-brothers' shared father-in-law is uncertain. The chronicle describes him as a nobleman from Kintyre, which suggests that he was a member of the Meic Somairle, since sources concerning this kindred link them with Kintyre more than any other region. The father-in-law, therefore, may well have been Rǫgnvaldr's first cousin Ragnall, or Ragnall's son Ruaidrí—both of whom appear to have been styled "Lord of Kintyre" in contemporary sources—or possibly Ragnall's younger son, Domnall. It is conceivable that the first union was undertaken before 1210, perhaps not long after 1200 considering the fact that Guðrøðr Dond—a product of Rǫgnvaldr's marriage—was apparently an adult by 1223 and had fathered at least one son by this date.