There is only two soby families in Denmark. the one in Jylland is from the town soby, where all the browncoal mines were, I am out of this family and now live in Australia. Migrated 1983. Plenty of the family however migrated to Canada and USA in the early 1900.
I believe however your family must be from a smaller island in Denmark, I cant remember what it is called, Possibly Lolland Falster. which is south of the Island Sealand, because my family tree has been researched, and No one migrated to Brazil. I hope that is of some help to you.