01
Define the shared requirement
Have the installer estimate each phase separately, including its specific details and allowances. Ask the supplier whether material can be selected together and how any reserved stock would be identified, stored, and released. Get the arrangement in writing rather than assuming a trade name guarantees a later matching lot.
02
Track what is actually retained
At the end of the first phase, reconcile unused material with the second phase's needs. Do not treat every leftover piece as interchangeable with every future detail. Keep size, thickness, selection, and condition records. Before phase two begins, review both stored material and any additional supply against the approved appearance and system requirements.