First time filling taxes?

I just started working in Oct 2025 and by the 31 Dec most probably my gross will be somewhere near 20k. I want to claim 3 adult dependents. On the other hand my brother he's been working for past 11 months and his gross would be somewhere around 65-67k. I was wondering should I claim all dependents or should he do it? Or maybe 2 to 1? We just want to maximize the tax return. Any help would be appreciated.