Sharing lightroom catalogs back and forth between photographer and culler/editor - corruption issue

Howdy! 

I'm working for a friend who owns a photography business. I'm culling and editing for her, but we live seven hours apart. 

She has been sharing catalogs with me for culling/editing purposes. 

Ex:

1. She sends "5-29-2022 Jacqui and Evan - TO CULL" from her computer (that has all original files)

2. I open catalog, cull photos, save a collection within catalog called "Culled", and send her back the .lrcat "5-29-2022 Jacqui and Evan - CULLED"

3. She opens catalog and makes edits to 25% of photos. Saves and sends it back to me as "5-29-2022 Jacqui and Evan - TO EDIT"

4. I open catalog and begin matching her edits. In theory, I would do the same thing as culling and send it back to her as "5-29-2022 Jacqui and Evan - EDITED"

However, the catalog was corrupted in between editing sessions (I have to cull/edit in the early mornings before my infant and toddler wake up). Here's the conundrum: if I exit Lightroom and shut down my computer in between sessions to avoid corruption, I won't be able to open the catalog back up because I receive the "file not found" message (all original files are on her computer/external, not mine). If I keep my lightroom open, I risk corrupting the catalog because I haven't properly shut my computer down for days. 

Thoughts?