I have just started my own detailed Family tree (Grant), however I came across information about the Grants in Norway, this was in an old document entitled "The Crondale Text". I will look it out for you but am unsure if its any help. It goes back to the Grants origin as vikings and then coming to Scotland and then here to Ireland, but some of the family went back to live in what's now known as Oslo.
Let me know if this is relevant its very general.
By the way my name is Mary Grant, Donegal Ireland. Bye