Start with records that explain the origin, ownership and movement of the actual money you propose to use, and an index describing what each record shows.
Do not invent missing links
A sale, distribution or transfer may involve several documents held by different people. List what is missing and who can retrieve it. Ask counsel which records the current process requires before purchasing translations or extensive professional reports.
A preliminary evidence map is not a final filing checklist. Collect the records that establish the two or three largest components of the account first, since those carry most of the weight and are usually the ones with genuine documentation behind them. Work outward from there.
Where a link in the history is missing, say so rather than substituting something that appears to fill the gap: a reconstructed schedule presented as though it were a contemporaneous record is worse than an acknowledged absence. Prefer documents created at the time and by someone other than the applicant, such as bank statements, tax filings, contracts and registry records. Where an institution can no longer produce a record, obtain written confirmation of that fact and keep it.
And avoid assembling a large volume of material that repeats the same point, since it obscures the parts of the account that actually need support.