If you only need to output RS232 and RS485, then there is no problem - one MAX232, one MAX485 and one cpu with a uart. Job done!

If you want to receive on both the RS232 and the RS485, then things get a little trickier. You need to explain how the communication is expected to take place and how you intend to arbitrate between RS232 and RS485. In some instances this may be very easy, other instances may be impossible. You may just need to add another uart or choose a micro with two uarts or maybe bit bash another uart...there's many solutions. Your title says you're a R&D engineer - you're paid to solve problems! At least that's what I'm paid to do.