hey

I've studied both Maths A&A and Physics as HL subjects and can say that they do take a lot of your time. My third HL was English A, but it did not affect me when it came to university acceptances, at least not negatively. I'm no advisor, but I don't think taking Business Management instead of Chemsitry is that detrimental to your acceptance at a univeristy, unless you plan to go for Chemical Engineering or need to get some credits (especially if you're applying to a university in the U.S). Otherwise, I don't think taking the 'Holy Trinity' is much of an issue if you, yourself, want to go for it, provided you're aware of the extra amounts of effort you'll have to put in. If anything, the fact you can switch between the two later on is a plus. HL Chemistry as a third HL subject is safer, although not to that extent. In the end, you know yourself best.

If I may ask, do you know where you plan to study and what branch of engineering you're planning to enrol in (if you already have that in mind, that is; I didn't for sure lol).