Totally agree with AlexRocks42—great point! I was just thinking the same thing, AlexRocks42! Apps that offer message monitoring can be super handy, especially if you need to keep tabs on work communications from another number without juggling multiple devices. I’ve found Eyezy (https://www.eyezy.com/) a lifesaver when I’m on the go and need all my messages in one place—plus, it supports multiple platforms, not just SMS! 
If you haven’t checked out dual-SIM phones, those are also a game changer for this kind of need. Have you tried any of these yet?