Apologies if this is already answered somewhere else here (if so, I could not find it).

I brought 500 images into Lightroom, made a number of adjustments to the first one, synchronized it to the rest, and then successfully created a star trails photo from them.

Then it occurred to me that these same images might make an interesting time lapse. Now, I’ve already made adjustments in LR, and I don’t want to re-do them. I understand that after identifying key frames the process, if your sequence is already in Lightroom, is as follows:
1. Set the filter to LTR Full Sequence
2. Go to gridview
3. Select all

But then the next instruction is:
4. Metadata -> Read metadata from file

And I get a warning message from LR:
This will overwrite the metadata in the Lightroom catalog with metadata from the file. This operation is not undoable

Does this mean that proceeding will erase all of my previous adjustments? I definitely don’t want that, because I put a great deal of time and effort into them.

What is the process to preserve existing adjustments?

Thank you!

If you "read Metadata" in Lightroom, you will take over the last version that you have in LRTimelapse.
So, if you edited in Lightroom _after_ doing your work in LRTimelapse, you should save metadata in LR, then go back to LRT, reload and apply the transitions, deflicker etc. again.
There is a tutorial in the expert tips section, where I show the process of reediting sequences correctly: https://lrtimelapse.com/tutorial/expert/
There you will also learn about "snapshots" in LRTimelapse which will allow you to preserve multiple edit versions of a sequence.

Thank you for the response -- much appreciated. However, this is not exactly my situation

>>So, if you edited in Lightroom _after_ doing your work in LRTimelapse, <<

I edited in Lightroom before doing ANYTHING in LRTimeLapse. I want to keep those edits when I use LRTImeLapse.

Thanks!

That's not how the workflow normally is supposed to work because LRTimelapse has some limitations with the tools that can be used / animated, for example the predefined masks etc.

If you didn't use too many masks (not more than 4) it might however work. If you load a preedited Sequence (from which you have saved the XMPs), LRTimelapse will try to take the edits over, as far as it is possible.
I'd recommend that you save a backup of your XMPs and just try it.
Next time just start your Workflow in LRT to be on the safe side.

Thank you, I will try that!