Keeping Proxies linked to Merged Clips after switching to a different computer

I created proxies from original high res clips on a Mac.

Then we moved the project (and all footage + proxies) to a second computer (PC) to create merged clips.

When we moved back to the original machine (Mac), high res clips relinked fine to the proxies but the proxies were not showing up for the merged clips. The high res clips have all their proxies attached - they dont show up for the merged clips. On the PC they do.

You can’t make/attach proxies from a merged clip. So we can't re-make or re-attach the proxies from the merged clips.

I tried making new proxies for the high res clips. They still dont show up on the merged clip. We have tried making new merged clips on the Mac and that works - the new merged clip shows up with proxies attached.  So we have to re-do ALL the merged clips on the Mac. That's one solution. BUT if we try to share the project across computers, then we will undoubtedly run into the same problem,. But we can’t just work on this project on one machine - we need to go back and forth.

Any ideas how to connect the proxies back to the merged clips?