Every Japanese learner is taught to understand the levels of politeness in speech, and adjust their language according to their conversation partner. However, I have never heard anything about how to speak when in a group setting, when the various people in the group are at different levels in the politeness hierarchy relative to you. Should you speak as though you are 1-on-1 with the person who would get the most polite speech from you? Should you adjust your speech depending on exactly who you are addressing with everything you say? What if you’re speaking to everyone?
To make things more concrete, I once was in a conversation with a close native speaker friend, with whom I speak in casual speech. Then, another native speaker who I didn’t know yet joined, and I decided in the spur of the moment that I should use です・ます forms with her, and continue using casual speech with my friend. I think this worked well, since I didn’t get negative feedback about it, but I didn’t know what to do when saying something that was addressed to both of them at the same time.
I can imagine situations where you would have an even larger gap in politeness between people - say, if you’re at work, talking to your boss and a younger coworker at the same time.
What do natives do in these situations? What would you do? Are there other situations that I didn’t mention that touch on this topic? Do the rules change as the number of people in the group changes?