I disagree. A gift is not income. Working for the money (walking dog) is income. I used $5 as an example. It could be $500.
I agree most kids do not report minor income like babysitting or a small tip, but it is supposed to be reported as income. All those $5 (or more likely $25) jobs can add up. Most do not report gifts even if they still have the cash or a gift card in their pockets, but it is an asset on filing day. A gift is not income, for the IRS or FAFSA
You are overthinking this. Your father makes $0. If the $10k received from you mother was for child support, report it. If it was for support of your father and grandfather, don’t report it (it’s not income)
If your grandfather is paying to support you all (all live together) that’s fine. Colleges will ask how you are supporting yourself if you report $0 income. At that time you can say you live with relatives.
We don’t know what money your father will receive is, so don’t know how to report. It could be a pension, so income (when received) or a forgotten utilities deposit (an asset when received), or a gift, or an inheritance. We don’t know.
Don’t have your grandfather’s money in your account on filing day or it will be hard to prove it is not your asset.