I can think of two options which might help you out.
Smart previews
I haven't tried this myself, but from the description of smart previews it seems that functionality is made for your scenario. The steps would roughly look like this:
- In LR select the files on your NAS which you want to edit. In your case that would be the
mytrip
photos on your NAS. Then click Library > Previews > Build Smart Previews
.
- After the smart previews are made, disconnect your NAS. LR will now switch to using the local smart previews.
- Assign the ratings and color labels.
- Delete the smart previews: in Library or Develop module, click
Library > Previews > Discard Smart Previews
.
If I understand the functionality correctly your LR catalog will link the ratings and color labels to the files on the NAS. Deleting the smart previews will not have any effect on that.
Locate missing folder
Using the [locate missing folder] functionality in LR your can relink your photos from local to NAS. These would be roughly the steps:
- Copy
mytrip
from NAS to local drive outside of LR (i.e. in Windows Explorer or Mac Finder)
- Import the local
mytrip
folder to LR.
- Assign the ratings and color labels.
- Outside of LR delete the local
mytrip
folder. LR will show that the folder is missing.
- Right click on the folder in LR and choose
Find Missing Folder
from the context menu.
- Select the
mytrip
folder on the NAS. In the catalog this relinks the ratings and color labels to the photos on the NAS.
Obviously I would test this out with a few photos first, before doing it with a batch to prevent loss of data.