EU income evidence and general inquiry.

So my family moved to the UK and got settlement status, I am classed as a home fee student, and my loan will be paid to me soon. I should be fine for next 2 years as they will be evaluated on the 2022/2023 & 2023/2024 tax years.

I am currently 18 and will likely not be eligible for independent status.

My problem is that my family is moving back to the EU and my 4th year loans will need to be based on their EU income.

I was just wondering how the evidence for that would work?
Will they accept translated p60 equivalent forms?
What if they are unemployed and don't have a p60 equivalent?
Any other problems I should be prepared for?