Hi everyone, initially I had a question on this, but now having explored the options myself, sharing the workaround with the community in hope existing user experience discrepancy is going to be resolved by Parallels in the future. Initially I wanted to resize/shrink guest macOS Tahoe 26.5 128GB (137GB as per Finder) virtual disk to a smaller 64GB - impossible in Parallels Desktop 26.3.2 on macOS Tahoe 26.5 host. I took several attempts with third-party disk cloning tools, tried diskutil from inside guest OS, taking out .hdd from .macvm package, etc. - nothing worked. The correct approach turned out to be 2-step (you may use just the first one for fresh install): create a new 64GB guest VM installation (Parallels Desktop 26.3.2 creates a default 128GB virtual disk when installing guest macOS (in my case, Tahoe 26.5) start the installation and go into "Configure" to configure manually as soon as it becomes available delete the 128GB virtual disk that has already been created and not resizable create the 64GB disk proceed with the installation use Apple Migration Assistant to migrate from 128GB installation into the new 64GB one make sure both source and target are upgraded to the same macOS version start MA on both proceed with migration Hope this helps!
