Relation riddle

Brother from one father
And son of my wife
Go and tell your father
His son is arrived
Husband of his wife.

There was once a young man who went travelling, leaving his wife and son behind at home. Time went by and his wife remarried, to the man’s own father, with whom she latter had a child. The years passed and one day the traveller returned home, only to hear that his wife had married his father and born him a son. Meeting the boy on the road home he recited the above riddle to order him to call their father.