Two Apple IDs on one iPhone - one for Apple Music, one for my personal library

I'm not sure I understand your answer. When I signed up for Apple Music, it immediately took over control and management of my personal library of mp3s. That is, I could still play tracks from my mp3 library and I could stream Apple Music. So I could do both with my one Apple ID. I don't want to co-mingle anything.

But Apple Music changed all the customized genre settings that I had meticulously maintained over the years. It also prevented all of my playlists - regular and smart, numbering several dozen - from syncing from iTunes to my iPhone. Some of my playlists were genre-specific, so it royally screwed up those tracks. And when it decided to change the genre settings on my mp3 tracks to the genres that it wanted, suddenly I had dozens and dozens of genres, many with just a few songs in each, which to me is worse than useless. (When I terminated Apple Music, I had to delete the Music app and then reinstall it, and then re-sync with iTunes and do a couple of other things, and thankfully that restored my personal library in my iPhone with my customized settings.)

So the thing is, I don't want Apple Music to manage my personal library. I just want to use Apple Music solely for its streaming library, and I want it to keep its grubby mitts off my personal library of mp3s.

That's the crux of my question. I wondered whether I could use one Apple ID to listen to my personal library and maintain my customized settings, and use a second Apple ID solely to access Apple Music's streaming service. If I'd have to sign out of one Apple ID and sign into a second Apple ID in order to keep Apple Music from touching my personal library, I'm perfectly fine with that minor inconvenience. But...can I do that? Would that accomplish what I'm trying to do?

The key point, the most important point, the only point that matters to me is: I don't want Apple Music to touch my personal library. So, is there a way to use Apple Music on the same device - my iPhone - where I maintain my personal library, but have Apple Music leave my personal library alone? Would 2 IDs do that?

What part is unclear? Well for starters, this: "That Apple ID can connect to your personal iTunes library, or Apple Music, but not both."

In point of fact, with my one Apple ID on my one iPhone, I was able to listen to my own music library (albeit corrupted by Apple Music) and I was able to stream Apple Music. It just depended on whether I tapped "Library" or "Explore" at the bottom of the screen. So that kinda contradicts your "but not both" comment, because I was using my iPhone with both. That's what's unclear.

This, too, was unclear: "You can only sign in to one iTunes account at a time." It was unclear in the sense that I'm not asking whether I can sign into two iTunes accounts at a time. I would be perfectly fine with logging out of iTunes Account #1 on my iPhone and logging into iTunes Account #2 on my iPhone IF doing so would allow me to use Account #1 to listen only to my curated library and Account #2 to listen only to Apple Music's stream (without messing up other iCloud things in the process).

But I've read elsewhere that doing that - signing out of one iTunes account and into a different iTunes account on the same iPhone - was do-able, but that it could spell trouble for calendar and contact integrity, etc. It sounded like more trouble and risk than it would be worth. But the overall information in that other source was incomplete and didn't specifically address my question, so I figured I'd get better info directly from an Apple discussion thread.

You listed three options. The second one says "...but don't enable the library." I assume by "the library" you mean I wouldn't enable my curated library when I sign in to Apple Music for its streaming service. But if my curated library is already on my iPhone, how would I "not enable" my library? Would it entail actually removing my library from my iPhone altogether before signing up for Apple Music? Or somewhere in the process of setting up Apple Music on my phone am I given the option to not enable my library, thus rendering my library inoperative on my iPhone but also preventing Apple Music from corrupting it?

I do appreciate all your information and the time you've taken, I just want to say for the record.