[wix-users] preventing double installs: per-machine & per-user both getting installed

[Alan Sinclair]

If I first install my package per-machine, then install the next version
per-user, I'm ending up with both sets installed. How can I prevent this?
Do I need some DLL custom action code to check for existing package
installed in the other scope?

I thought that FindRelatedProducts would recognize the first package and
turn the second install into an upgrade, but that's not happening. The log
shows this:

MSI (c) (7C:58) [15:45:55:699]: FindRelatedProducts: current install is
per-user.  Related install for product
'{01855CFB-CD94-4046-B41A-60E1F7DC1325}' is per-machine.  Skipping...


Here's my code

    <Product Id='*' UpgradeCode='AC9825C9-8164-4A7A-B575-FA557EED9A4C'
        Name="!(loc.ApplicationName)" Manufacturer='!(loc.ManufacturerName)'
        Version="$(env.PRODUCT_VERSION_DOTTED)" Language='1033'
Codepage='1252' >

        <Package Id='*'
            Manufacturer='!(loc.ManufacturerName)'
Platform="$(var.V_PLATFORM)"
            InstallerVersion='300' Languages='1033' Compressed='yes'
SummaryCodepage='1252' />

        <Upgrade Id='AC9825C9-8164-4A7A-B575-FA557EED9A4C'>
            <UpgradeVersion OnlyDetect="yes"
Minimum="$(env.PRODUCT_VERSION_DOTTED)"
                Property="NEWERVERSIONDETECTED" IncludeMinimum="no" />
            <UpgradeVersion OnlyDetect="no"
Maximum="$(env.PRODUCT_VERSION_DOTTED)"
                Property="OLDERVERSIONBEINGUPGRADED" IncludeMaximum="no" />
        </Upgrade>

        <InstallExecuteSequence>
        <!-- block downgrades for silent installs -->
            <Custom Action='PreventDowngrading' After='FindRelatedProducts'>
                NEWERVERSIONDETECTED
            </Custom>
            <!-- remove old packages -->
            <RemoveExistingProducts Before='InstallInitialize'/>
        </InstallExecuteSequence>

        <InstallUISequence>
          <!-- when running with UI block downgrades before the Welcome
screen appears -->
            <Custom Action='PreventDowngrading' After='FindRelatedProducts'>
                NEWERVERSIONDETECTED
            </Custom>
        </InstallUISequence>

        <CustomAction Id='PreventDowngrading' Error='!(loc.PreventDownMsg)'
/>

        <Directory Id='TARGETDIR' Name='SourceDir'>

         [etc.]


Any suggestions will be much appreciated!

Incidentally, I'm not using the MajorUpgrade element because when I do so I
cannot sequence RemoveExistingProducts, which I must have to uninstall a
different package .. an older MSI with different UpgradeCode, using this
code:

        <Upgrade Id="A2344ED4-1A07-9AAE-78AE-0A1BCD932E37">
            <UpgradeVersion OnlyDetect="no"
Property="PREWIX_PACKAGE_FOUND"  Minimum="0.0.0" />
        </Upgrade>

Thanks
Alan