Ariz. Rev. Stat. § 48-3250
If the committee determines at any time that it is necessary or desirable to change or deviate from the terms, conditions and proposals of the plan adopted and set forth in the bondholders' agreement, it shall reduce the proposed change or deviation to writing and submit it to the board of directors for approval or rejection. If the proposed change or deviation is approved by the board of directors, the committee shall mail a copy thereof, postage prepaid, to each bondholder who has deposited his bonds to the last known place of residence of the holder. The changes or deviations proposed by the committee and approved by the board of directors shall become a part of the bondholders' agreement and binding upon all bondholders who have not withdrawn their deposited bonds within thirty days from the date of the deposit of the copies of such notice in the United States post office at the city of Phoenix.
A.R.S. § 48-3250