Tried to Import pics from another catalogue... fail

Firstly, thank you to anyone who can help me with this. I am a longtime user of LR, but I always use it for the same things, so as a result, I am completely useless when it comes to other functionality of the software.

My LR set up is on my iMac. My Raw files are on an external, and my catalogue is on Dropbox. I just took some photos and edited them on my Macbook in a temp catalogue. I just tried to move the images from my Macbook Pro into my iMac (main system) and I've completely screwed it up.

• Firstly I opened my iMac LR system (the main one) and chose to "Import from another catalogue." I selected the temp catalogue, and chose to import.
• The folders didn't appear in LR, so I quit and rebooted LR. Still nothing. Then I chose to "Synchronise the folder" - Now the images and folders appeared, but with none of the edits I previously made.
• I also now have 3 LR catalogues in my Dropbox (the main one and 2 x "conflicted copies"

When I select one of the moved photos and chose "show in finder" the raw file is in the right place, but there is no XMP side car file.

How do I identify which LR catalogue to use moving forward, given that I now have 3.

Can anyone help me here?

Thanks !