WiX how to define multiple HarvestPaths

I'm trying to build an installer using WiX. My software provides updates for different versions (V23, V22, V21, and so on). I'm using Heat to generate the list of required libraries (including my own) dynamically.
I'd like my Installer to:

1. Be a single installer that installs the content for all releases in a single folder (with each version in their respective subfolders). This is because a single user might use different versions of our software at the same time.
2. The installer should correctly grab the builds of each year when creating the installer.

The easiest way I could think of doing this would be to have three different harvest paths, one for each heat generated list of DLLs. However, wix/heat doesn't allow me to name the harvestpath anything other than HarvestPath, so the following doesn't work. It still highlights what I want to achieve, which is why I'm posting it here nonetheless.
How would I achieve what I'm trying to do here?

Installer.wixproj

<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|x86' ">
    <OutputPath>bin$(Configuration)\</OutputPath>
    <IntermediateOutputPath>obj$(Configuration)\</IntermediateOutputPath>
    <DefineConstants>HarvestPath23=..\MySoftware\bin\REL23\</DefineConstants>
    <DefineConstants>HarvestPath22=..\MySoftware\bin\REL22\</DefineConstants>
    <DefineConstants>HarvestPath21=..\MySoftware\bin\REL21\</DefineConstants>
    <Cultures>en-US</Cultures>
</PropertyGroup>

<ItemGroup>
    <Compile Include="Product.wxs"/>
    <!-- This is the Heat created one for 23 -->
    <Compile Include="HeatGeneratedFileList23.wxs"/>
    <!-- This is the Heat created one for 22 -->
    <Compile Include="HeatGeneratedFileList22.wxs"/>
    <!-- This is the Heat created one for 21 -->
    <Compile Include="HeatGeneratedFileList21.wxs"/>

</ItemGroup>

<Target Name="BeforeBuild">
    <HeatDirectory Directory="..\MySoftware\bin\REL23\" PreprocessorVariable="var.HarvestPath23" OutputFile="HeatGeneratedFileList23.wxs" ComponentGroupName="HeatGenerated23" RunAsSeparateProcess="$(RunWixToolsOutOfProc)" DirectoryRefId="INSTALLFOLDER23" AutogenerateGuids="true" ToolPath="$(WixToolPath)" SuppressFragments="true" SuppressRegistry="true" SuppressRootDirectory="true"/>
    <HeatDirectory Directory="..\MySoftware\bin\REL22\" PreprocessorVariable="var.HarvestPath22" OutputFile="HeatGeneratedFileList22.wxs" ComponentGroupName="HeatGenerated22" RunAsSeparateProcess="$(RunWixToolsOutOfProc)" DirectoryRefId="INSTALLFOLDER22" AutogenerateGuids="true" ToolPath="$(WixToolPath)" SuppressFragments="true" SuppressRegistry="true" SuppressRootDirectory="true"/>
    <HeatDirectory Directory="..\MySoftware\bin\REL21\" PreprocessorVariable="var.HarvestPath21" OutputFile="HeatGeneratedFileList21.wxs" ComponentGroupName="HeatGenerated21" RunAsSeparateProcess="$(RunWixToolsOutOfProc)" DirectoryRefId="INSTALLFOLDER21" AutogenerateGuids="true" ToolPath="$(WixToolPath)" SuppressFragments="true" SuppressRegistry="true" SuppressRootDirectory="true"/>
</Target>

Product.wxs

    <Feature Id="ProductFeature23" Title="My super software 2023" Level="1"
             ConfigurableDirectory="INSTALLFOLDER23">
        <ComponentGroupRef Id="HeatGenerated23"/>
        <ComponentGroupRef Id="ProductContents"/>
    </Feature>
    <Feature Id="ProductFeature22" Title="My super software 2022" Level="1"
             ConfigurableDirectory="INSTALLFOLDER22">
        <ComponentGroupRef Id="HeatGenerated22"/>
    </Feature>
    <Feature Id="ProductFeature21" Title="My super software 2021" Level="1"
             ConfigurableDirectory="INSTALLFOLDER21">
        <ComponentGroupRef Id="HeatGenerated21"/>
    </Feature>
</Product>

<Fragment>
    <Directory Id="TARGETDIR" Name="SourceDir">
        <Directory Id="CommonAppDataFolder" Name="MyAppDataFolder">
            <Directory Id="DIR_FOO" Name="FOO">
                <Directory Id="DIR_Contents" Name="Contents">
                    <Directory Id="INSTALLFOLDER23" Name="2023"/>
                    <Directory Id="INSTALLFOLDER22" Name="2022"/>
                    <Directory Id="INSTALLFOLDER21" Name="2021"/>
                </Directory>
            </Directory>
        </Directory>
    </Directory>
</Fragment>

The OP answered the question but here is why it works. The following in MSBuild snippet:

<PropertyGroup>
  <DefineConstants>HarvestPath23=..\MySoftware\bin\REL23\</DefineConstants>
  <DefineConstants>HarvestPath22=..\MySoftware\bin\REL22\</DefineConstants>
  <DefineConstants>HarvestPath21=..\MySoftware\bin\REL21\</DefineConstants>
</PropertyGroup>

is essentially the same in the C#/C/C++ snippet:

int DefineConstants;
DefineConstants = 1;
DefineConstants = 2;
DefineConstants = 3;

In both cases, the DefineConstants value gets set to the last assignment. There are two ways to fix this in MSBuild syntax, combine into one assignment

<PropertyGroup>
  <DefineConstants>
    HarvestPath23=..\MySoftware\bin\REL23\;
    HarvestPath22=..\MySoftware\bin\REL22\'
    HarvestPath21=..\MySoftware\bin\REL21\
  </DefineConstants>
</PropertyGroup>

(note: the white space gets ignored)

Or, concatenate the variable name on each line like:

<PropertyGroup>
  <DefineConstants>$(DefineConstants);HarvestPath23=..\MySoftware\bin\REL23\</DefineConstants>
  <DefineConstants>$(DefineConstants);HarvestPath22=..\MySoftware\bin\REL22\</DefineConstants>
  <DefineConstants>$(DefineConstants);HarvestPath21=..\MySoftware\bin\REL21\</DefineConstants>
</PropertyGroup>

Note: This really has nothing to do with the WiX Toolset and everything to do with MSBuild syntax.

Ok I actually managed to do exactly what I wanted by just defining all three HarvestPaths in one DefineConstants context instead of three separate ones.
So in the code sample above, instead of this:

<DefineConstants>HarvestPath23=..\MySoftware\bin\REL23\</DefineConstants>
<DefineConstants>HarvestPath22=..\MySoftware\bin\REL22\</DefineConstants>
<DefineConstants>HarvestPath21=..\MySoftware\bin\REL21\</DefineConstants>

use this

<DefineConstants>HarvestPath23=..\MySoftware\bin\REL23\;HarvestPath22=..\MySoftware\bin\REL22\;HarvestPath21=..\MySoftware\bin\REL21\</DefineConstants>

and all the rest works fine!