bcedit.ps

# Requires running as Administrator
# This is a simplified example and may need modifications to work in your environment

$windowsInstallations = Get-WindowsInstallations # Custom function to detect Windows installations
foreach ($install in $windowsInstallations) {
    $description = "Windows on " + $install.DriveLetter
    $guid = (bcdedit /copy {current} /d $description).Trim().Split(" ")[2]
    
    bcdedit /set $guid device partition=$install.DriveLetter
    bcdedit /set $guid osdevice partition=$install.DriveLetter
}