How to pack linked files from referenced NuGet packages

I have a build-properties-defining package that is to be used by all the libraries.
Some libraries may provide a json file, that should be retained when they're referenced by some other libraries and then, ultimately, all the configuration files should be transitively provided to a consumer of a top-level library.

There's a convention, that libraries place their configuration files into an appsettings/cfgs directory.

Currently I have the following in my build-defining package's xxx.targets file

...
<ItemGroup>
  <Content Include="$(ProjectDir)\appsettings\cfgs\*.json">
    <CopyToOutputDirectory>Always</CopyToOutputDirectory>
    <Pack>true</Pack>
    <PackagePath>contentFiles\any\any\appsettings\cfgs</PackagePath>
    <PackageCopyToOutput>true</PackageCopyToOutput>
  </Content>
</ItemGroup>
...

What works when using the target file above:

when a json file is added to appsettings/cfgs, it is copied to build output by default
when a json file is added to library's appsettings/cfgs, it is packed into library's NuGet package via dotnet pack
when a library is referenced, its' configuration files are shown in solution explorer as appsettings/cfgs linked directory and linked files are copied to consumer's output.

What doesn't work: I have library1, that provides a configuration file 1.json. I have library2, that consumes library1's NuGet package:

1.json is shown in solution explorer
1.json is copied to library2's output on build
1.json is NOT, despite my best efforts, included into library2's NuGet package, while library2's json files, lying in the same very directory of output, are successfully packed.

How do I ensure that files, linked from referenced NuGet package, are added to consuming library's NuGet package, produced by dotnet pack?

provided by libraries, are packed into a NuGet package

Solution

As I couldn't find a complete answer for my case, I'll provide a solution that works for me so far.

My xxx.targets looks like this now

<ItemGroup>
  <Content Include="$(ProjectDir)\appsettings\**\*.json">
    <CopyToOutputDirectory>Always</CopyToOutputDirectory>
    <!-- Target below will ensure that the configuration files are correctly packed -->
    <Pack>false</Pack>
  </Content>
</ItemGroup>

<Target Name="PackConfigurationFiles" AfterTargets="Build">
  <ItemGroup Condition="'$(IsPackable)' == 'true'">
    <Content Include="$(TargetDir)appsettings/cfgs/*.json">
      <Pack>true</Pack>
      <PackagePath>contentFiles\any\any\appsettings\cfgs</PackagePath>
      <PackageCopyToOutput>true</PackageCopyToOutput>
    </Content>
  </ItemGroup>
</Target>

So, instead of relying on dotnet pack to pick up linked files (which it doesn't so far), we're specifically using appsettings/cfgs directory in build output, where all our linked configuration files are in fact present along with consumner's own json files, if any.