Acts 19:14

And there were seven sons of one Sceva, a Jew, and chief of the priests The Greek says simply a chief priest, and so Rev. Ver.We cannot tell why the title is given to him, but it is most likely that the name was applied to the heads of the twenty-four courses of the Levitical priesthood, who are called in the Old Testament "heads of fathers" houses."

which did so i.e. which agreed to adopt this form of words in their exorcisms. There is no need to suppose that the whole seven were present in the case about to be named, but only that they were all exorcists, and in their wish to seem the best of their class they determined to use words which should connect them with the Christian preacher through whom many miracles were known to have been wrought.