A dated record of the official terms as they stood when decisions were made, written confirmation of who receives each payment and at what stage, and the underlying evidence for the immigrant category relied on afterwards. Intermediary summaries are not a substitute for any of these.
Record the terms, not somebody's description of them
Hypothetical example: Bronwyn is assembling a file on the Gold Card process for her Callander household. Three kinds of record matter here. The first is evidence of what the official framework said on the day money moved, kept as a dated capture of the official page and FAQ rather than as a consultant's slide.
The second is the payment trail: who was paid, by whom, at what stage, and on what authority, with the same care anyone would apply to a large transfer to an unfamiliar recipient. The third is the substantive file for whichever employment-based category will actually be used, which is where a professional applicant's qualifications, achievements or offer of employment are evidenced. Bronwyn should also keep her own notes of what she was told by anyone facilitating the process, because a mismatch between that and the official terms is the earliest available warning that something is wrong.
Where an intermediary declines to put its description of the process in writing, the refusal is itself the answer to the question being asked, and it should end the conversation rather than prompt another one.