How do I delete photos from a finished iMovie (11) project, but not the audio?

I completed a project and after many months am coming back to re-edit. I need to remove some, and extend the timing on the previous and former to make up for the gap, and simply replace others. Each time I delete the photo from the event library, I also loose a portion of the audio track.

I do recall when making this film in the previous version, that I had to export the photos and audio, and then import and overlay the music as one audio track was getting lost to the other. I am pulling my hair out afraid that I have to start from further back than I'd hoped. Thank you very much for anyone's help in advance.

RM