from the form's instructions: Form 56 should be filed by a fiduciary to notify the IRS of the creation or termination of a fiduciary relationship under section 6903. For example, if you are acting as fiduciary for an individual, a decedent’s estate, or a trust, you may file Form 56.
Fiduciary. A fiduciary is any person in a position of confidence acting on behalf of any other person.
so you should file.