to elaborate on this welfare system pro tip: suppose you lack documentation for a fact, but you had in-person meetings with person X in the welfare system about it over an extended period of time.
for lack of hard evidence, a person within the system who has talked to you can confirm that you've been saying the same thing for a long time, and that can help quite a lot.
they trust it more when another person than you says it. that's psychology, so use it to your advantage.