So I was just re-reading wherein the older brother of the gay main protagonist who disapproved of his homosexuality actually finds himself having feelings for another guy.
Well, the uke is also in the same situation but the best thing about the seme's brother's situation is that we actually get to read the seme's reaction when he finds out his straight brother may also be gay.

So I was thinking I'd like to read other manga with this same situation. It's ok if the gay brother does not find out but a bonus if he does.

I think something a bit like this occurred in Self portrait

I also read one the other day where one brother starts falling for a science teacher who heads a science club he is in. And his older brother reckons the teacher is suspicious and disapproves and is always trying to interfere. But he then falls for his classmate who was in an accident and has a bad memory so writes stuff in a book to remember it.
Lol can't remember the name but yeah I've already read that one thanks

Any recommendations much appreciated ^_^

I think the manga you are looking for is Kagakushitsu e Douzo

Well that's the one I described having read, thanks
But I'm looking for recommendations with situations like what I described.

Rakka Sokudo

The brother confides his concerns about his gay brother to a work friend, then himself becomes involved with the friend. There is a moment of reveal, as I recall.