Your brother needs to open his own account.
In general -
4 years of english
4 years of foreign language (or reaching level 4)
4 years of history
4 years of math, reaching Calc if offered
4 years of science - 1 year of bio, chem, and physics and one of those at the AP level (I’d recommend AP physics C for a prospective engineer).
1 year of fine arts is also required at some schools.
Don’t skimp on core courses to try to “specialize”.
If you have room for electives, then CS would be helpful and trying to fit in AP chem.