Every included person needs their own set of records — passport, civil documents, and background information — because each is assessed individually. Supporting documents go with Form I-140G through the official portal after USCIS issues instructions, and more can be requested later. Start with whichever certificate takes longest to obtain in the family's home jurisdiction.
Keep one file per person
Four sets of paperwork are easy to mix up, so keep a separate folder for each person and a single index showing what exists, what is ordered, and what is missing. Track passport expiry dates for the children, since these often fall sooner than an adult's. Note documents needing certified translation.
When official instructions arrive, the family is then assembling from an inventory rather than starting a search. Add two habits that make four parallel files manageable. Record on the index not only what each document is but when it was obtained and when it expires, since certificates, police records and passports all age differently and a family that starts assembling early can find its earliest documents stale by the time the rest arrive.
And note for each item how long a replacement would take, so a lost or superseded document is a scheduling entry rather than a crisis. Hypothetical example: a family completes three of four sets in six weeks and the fourth takes seven months, by which time two documents in the first set need reissuing — a sequence that is entirely predictable from an index carrying dates and considerably harder to see from four folders on a shelf.