Copying files from an inherited nuget

I've developed a custom NuGet which uses DotNetProjects.DotNetSiemensPLCToolBoxLibrary. DotNet library icludes external dlls that are copied into the output directory following these statements:

<Content Include="..\externalDlls\libnodave_jfkmod.dll"><Pack>true</Pack><PackageCopyToOutput>true</PackageCopyToOutput><CopyToOutputDirectory>Always</CopyToOutputDirectory></Content><Content Include="..\externalDlls\libnodave_jfkmod64.dll"><Pack>true</Pack><PackageCopyToOutput>true</PackageCopyToOutput><CopyToOutputDirectory>Always</CopyToOutputDirectory></Content>

However, when my custom Nuget is used in another project, dlls from DotNet nuget are shown on project tree but not copied into the output directory.

nuget use example

If I modify manually the content properties to set that these dlls will always be copied into output directory it works. It is posible to do so in the .csproj of my custom nuget?.