i always get Seer Blessed houses and Grandfathered houses confused.
Seer Blessed are the same as Grandfathered but you can openly trade them and they do not count against your housing limit, Grandfathered from what i have heard over the years you can do nothing with.
while i got rid of both of the above years ago i have a guild mate who has an account that is chalked full of Grandfathered houses and his are all still the original houses that where placed, i would think that since they historically wanted us all to get out of the grandfathered houses business that they would not be allowing us to do anything with them.
guess it comes down to do you wish to test the waters and risk loosing your grandfathered house.
for me it was a easy decision, get a castle where i wanted it or keep my 5 side by side houses (L shapes on both ends with 3 thatched roof cabins in the middle)