MSBuild (for Delphi) Make-like functionality - delphi

Question

I am trying to set up dependencies for a set of Delphi packages, such at if Application A uses Package 1 and Package 2, and Application B uses Package 1 only, then only Application A is rebuilt when Package 2 is changed.
At the moment, I am using a Group File, and each Package and Application is built (re-linked), even if it or one of it's dependencies is not changed.
UPDATE:
Unit1.pas is in Package 1
Unit2.pas is in Package 2
Application A uses Package 1 and Package 2
Application B use Package 2
What I want is that if I change Unit1.pas, then ONLY Package 1 and Application B is rebuilt. make will do this, but I can't work out how MSBUILD could be made to work.
My worked example uses a group file, which might be the underlying problem.

Answer 1

OK, I think I have sorted this out. Groupprojs will always rebuild / relink, so that is not what I want.
I have created a targets file, such that it defines the 4 projects and the dependencies of each. It has to be all the dependencies, both code and binary (i.e. the packages).
Msbuild has an attribute 'DependsOnTarget', but this doesn't achieve what I want, so I have added dependencies on both the code and packages. The final build.targets file looks like this ...
<Project ToolsVersion="3.5"
xmlns="http://schemas.microsoft.com/developer/msbuild/2003"
DefaultTargets="Default">
<ItemGroup>
<Package1 Include=".\Package1\Package1.dproj"/>
<Package2 Include=".\Package2\Package2.dproj"/>
<App6 Include=".\App6\Project6.dproj"/>
<App7 Include=".\App7\Project7.dproj"/>
</ItemGroup>
<ItemGroup>
<Package1ExternalSourceFiles Include=".\Package1\*.pas" />
<Package2ExternalSourceFiles Include=".\Package2\*.pas" />
<App6ExternalSourceFiles Include=".\App6\*.pas" />
<App7ExternalSourceFiles Include=".\App7\*.pas" />
<Package1BinaryFiles Include=".\Package1\Win32\Release\Package1.bpl" />
<Package2BinaryFiles Include=".\Package2\Win32\Release\Package2.bpl" />
<App6BinaryFiles Include=".\App6\bin\Project6.exe" />
<App7BinaryFiles Include=".\App7\bin\Project7.exe" />
</ItemGroup>
<Target Name="App6" Inputs="#(App6ExternalSourceFiles);#(Package1BinaryFiles);#(Package2BinaryFiles)" Outputs="#(App6BinaryFiles)" DependsOnTargets="Package1;Package2">
<Message Text="App6" />
<MSBuild Projects="#(App6)"/>
</Target>
<Target Name="App7" Inputs="#(App7ExternalSourceFiles);#(Package1BinaryFiles)" Outputs="#(App7BinaryFiles)" DependsOnTargets="Package1">
<Message Text="App7" />
<MSBuild Projects="#(App7)"/>
</Target>
<Target Name="Package1" Inputs="#(Package1ExternalSourceFiles)" Outputs="#(Package1BinaryFiles)">
<Message Text="Package1" />
<MSBuild Projects="#(Package1)"/>
</Target>
<Target Name="Package2" Inputs="#(Package2ExternalSourceFiles)" Outputs="#(Package2BinaryFiles)">
<Message Text="Package2" />
<MSBuild Projects="#(Package2)"/>
</Target>
<Target Name="Build">
<CallTarget Targets="Package1;Package2;App6;App7"/>
</Target>
</Project>
Whether this is scalable I am not sure, we could potentially have a large number of projects and dependencies.
UPDATE: Actually the binary dependency on the Applications isn't needed, if they are shipped separate from the packages. Recompiling Package 1, without changing it's interface would mean that App6 and App7 are not rebuilt.