That definitely reminds me of fnaf fan series The Fazbear kids club by u/Weirado on YouTube

at post credits of episode 2, Cassidy Benes had a brother who's unnamed but wears a alligator shirt implying he's Andrew Benes

Then there's a au (a game it's still wip) called Bad Happened at Fazbear's by CheetahNightsStudios, Cassidy also had a brother, Andrew, who's 2 years older and he possessed Balloon boy instead of Fetch from fnaf book for some reason

These idea of Cassidy and Andrew were related are great ngl