Does financial aid affect international students?

I do believe that financial aid does not take his criteria into consideration from all the information I have read. I have a relative who told me that in many cases the scholarship money does not fully cover the various needs of the scholarship recipient. Is this really the case? He told me that he plays 1 euro casino games, to earn money without risking too much.

(First off, I'm answering specifically for American colleges—I can't say for universities outside the US.)

This is a more complicated question than it might seem, but the short answer is yes, your international status will typically affect what you might be offered in financial aid (this is not specific to being Nigerian, just specific to not being a US citizen or permanent resident). There is a small list of generalized colleges that are need-blind and meet full financial need for international students; those are Harvard, Yale, Princeton, Amherst College, and MIT. There's a somewhat larger list of schools that are need-aware—which means gaining admission will be harder for you because you're applying for financial aid—but will still offer as much financial aid as they think you need to attend. They're listed on this Wikipedia page, which is honestly the clearest and most straightforward resource for this: https://en.wikipedia.org/wiki/Need-blind_admission#U.S._institutions_that_are_need-blind_and_meet_full_demonstrated_need_for_both_U.S._and_international_students.

For those schools, they would actually offer you more money in the years that your sister is studying at her American university and there will be a section on the financial aid application (the CSS Profile) that asks for that information. However, they will stop considering that once she graduates, and you'd likely see your aid package reduced after that point.

For merit aid, you might get some money from schools you're overqualified for in terms of academics (so basically schools that would show up as "safety" on CollegeVine's chancing list). For larger, more prestigious schools that are not on the list I linked above, you'd like have to pay close to full price, as many of those schools admit international students expecting them to pay the full cost of tuition.