What is the correct way to sync with audio? Example scenaria

Trying understand how to work with event recordings and sync. It seems that there is some disagreement on techniques on this forum. Some have been asking for a ‘sync in timeline’ feature (like other programs have) for awhile. But others declare that you don’t need that if you simply sync all your content before you start. Since I’ve had trouble with the new Beta17 ‘sync in timeline’ function, I’m trying to revisit this to hopefully learn how this should be done. I will describe 3 different scenarios.

A) I record 4 video feeds to a Shogun 7. During the event I perform live switching between the sources. When it’s time to edit, I import the XML file that the Shogun creates and walla, my content is imported as a multicam clip with all of my live cuts in place. But how do I sync this with an external audio track that I recorded? Or, how do I add content from a camera that was not feeding the Shogun (but has syncable audio recorded in it)? With version 17 I can try to sync these pieces in the timeline. But 1) I’m having trouble with this working (tries and says "No match was found when attempting to sync these clips") and 2) how would I approach this with version 16?

B) Again with the Shogun 7, I record 4 streams and live switching. But this time I have some gaps in the recordings (either by accidentally stopping the recorder during the event or because, well, sometimes it just happens). I have continuous backup records in a camera (complete with ‘reference’ audio) and a standalone audio recording. I’d like to use the Shogun content that I have but fill in any video gaps from the camera backup. I’ve found that I can import each timeline separately and then drag them into a main timeline. But I haven’t been able to sync them to my main audio track with Beta 17 and the ’sync in timeline’ feature. Resolve tries and says it can’t. I CAN choose to lose my switching data and simply combine all of my media into one multicam clip but the audio choices are slim. For instance, I have a stereo ambience mic track that is typically recorded and mixed into the Shogun. But in this case, because the Shogun recording isn’t continuous, I have those as separate tracks. The ambient won’t likely sync via waveform with the other clips. If I can find the start of my main audio track then I can simply align this ambient one to it’s start. But the multicam clip starts when the backup camera record starts. It’s not the correct start time.

C) I have content from several cameras and audio devices and would like to start editing. But, I don’t have all the content yet. If I follow the ’sync all media before you edit’ approach then I think that I have no choice but to wait for the last of the content OR try to shoehorn it in manually when it does arrive. Or, is there a way to add content to an already existing multicam clip?

You can always open a multi-cam clip as a timeline and drop new media into it. And you can sync audio in that "timeline", I think. (I haven't done it, so maybe it doesn't work as expected, but I think this could answer most of your questions.)

In terms of Sync in Timeline not working, under what conditions? With adjacent clips in the same audio track? With multiple linked video/audio clips? I've noticed some situations where it doesn't work, but so far it has seemed to be in cases where what I'm asking it to do doesn't make sense in the end. Or maybe I've just convinced myself that's the case.

With version 17 I can try to sync these pieces in the timeline. But 1) I’m having trouble with this working (tries and says it can’t do it) and 2) how would I approach this with version 16?

It's either that or multicam or in 17 and not possible in 16.

Have a look at PluralEyes, it's simply the best for syncing by waveform. AFAIK there is a time-limited demo.
If even that program refuses to sync, your recordings have a problem.

You can always open a multi-cam clip as a timeline and drop new media into it. And you can sync audio in that "timeline", I think. (I haven't done it, so maybe it doesn't work as expected, but I think this could answer most of your questions.)

Sync is indeed an available option when "open in timeline" is used to peer into the multicam clip. But I'm finding that sometimes it will sync with an audio file dragged into that timeline and sometimes it won't.

In terms of Sync in Timeline not working, under what conditions? With adjacent clips in the same audio track? With multiple linked video/audio clips? I've noticed some situations where it doesn't work, but so far it has seemed to be in cases where what I'm asking it to do doesn't make sense in the end. Or maybe I've just convinced myself that's the case.

You cannot sync audio in the timeline if the audio clips are not on different tracks so I'm not making that mistake.

I'll try to explain some of what I'm seeing.
I can go to the media tab and select one of the original video clips from the Shogun that is used in the multicam clip and create a new multicam clip with it and an imported audio file, sync'd with audio waveform. But I cannot create a new mulitcam clip out of the multicam clip (that appears to be using the exact same audio track) and that same bare audio file. It will not sync. I'm sure this is getting very hard to follow. It's difficult to describe.

I have to think that there is some layer of this onion causing the problem but I haven't found it yet.

One thing that I'm very much not clear on is just how the audio is "output" from a compound (multicam) clip. If I open a multicam clip in timeline and muck around with it with the Fairlight mixer settings, those settings disappear as soon as I follow the breadcrumbs back to the original timeline. In fact, not only do I not hear them, if I open the multicam again in timeline, all my changes (effects etc) are gone.

Another thing is that I can't mute audio tracks in that sub timeline without also muting the associated video track. If I unlink the video and audio clip then I can use the "d" key to disable the audio separately from the video but the mute button on the audio track will always mute both the audio AND the video.

I can apply color changes to the video clips when opened in the timeline and those are still active when I move back to the main timeline. But audio changes (except for disabling audio tracks altogether) don't stick.

Have a look at PluralEyes, it's simply the best for syncing by waveform. AFAIK there is a time-limited demo.
If even that program refuses to sync, your recordings have a problem.

I hate to drag another app into this. Resolve shouldn't have a problem synchronizing these audio files.

As far as whether these recordings having a problem, Resolve doesn't seem to have any issues with syncing any of my audio tracks (in the project I'm currently working on) with each other when I'm working with plain media files. It's the multicam clips that are not acting as expected. And I'm trying to understand what is going on under the hood to perhaps find a way around it.

You may want to describe this in the forum for beta 17, as it's still under construction.
From my experience with 16, you have to stick to one multicam clip from it's construction, there is no adding up.

A) But how do I sync this with an external audio track that I recorded?

In 16, manually.

Add it under the Multicam and move it into place.

B) simply combine all of my media into one multicam clip

Add only camera media to a Multicam. Always keep usable audio out of the Multicam. (It makes mixing it Fairlight later on soooooo much easier.)

C) is there a way to add content to an already existing multicam clip?

Right click the Multicam>Open in Timeline.

But again, only add camera media to a Multicam.