Interpreter stays in their role no matter what
An interpreter’s role is to faithfully interpret. That’s it. The interpreter may be able to provide some useful general information about deaf people or interpreting beforehand if it helps the assignment go more smoothly, but that is all. During the assignment, the interpreter must stay in his or her role. She is not a notetaker, CPR dummy, or animal holder (yup – happens all the time).

If a hearing client asks the interpreter a question directly during an assignment, this can cause confusion for the deaf person. The deaf person will think: Who is speaking? Is the interpreter sharing what the hearing person is saying, or is the interpreter answering the hearing person’s question directly as themselves?

Interpreting requires such intense concentration that interpreters often work in teams. If the assignment is more than two hours, two interpreters should be hired in order to ensure accurate interpreting.

http://carolafinch.hubpages.com/hub/Characteristics-of-Effective-Sign-Language-Interpreters 11092015