A dated copy of the official program page and any implementing executive action, the intermediary's written material and contract, and a complete record of any payment including payee, instrument and date.
Build a dated record because the terms move
Hypothetical example: the operator relies on a consultant's summary written some months earlier and never sees the official material. Keep a file that would let someone else reconstruct the decision. Save the official page as a dated PDF each time it is consulted, together with any announcement that changed it.
Save the intermediary's brochure, emails and contract, including what they charge, what they promise and what they will refund. Save the payment record: who was paid, from which account, under which instrument and on what date. Save a written list of the questions that could not be answered from official sources.
If a family member or adviser later asks why a decision was made, that file answers it, and if the terms change again the file shows exactly what was relied on. Do not keep credentials or banking passwords in the same place.