How can I copy plug-in DLLs from a sub folder using NuGet

For a .NET Framework project (SDK style) I'm trying to create a Nuget package including code, documentation and additional plug-ins from a user control.

After creating my NuGet package and using it in a test project, all that's being copied when I build my test project is the code, the documentation and the .\de resource directory content, but not the bin and bin64 directories' content containing the plug-ins.

How can I make the content of the bin and bin64 directories copied, too?

Here's the directory structure of my NuGet package source:

Package.nuspecReadMe.md     contentFiles\any\any\Barcode.Windows.Forms.xml       contentFiles\any\any\Barcode.xmlcontentFiles\any\any\DocumentServer.Windows.Forms.xmlcontentFiles\any\any\DocumentServer.xmlcontentFiles\any\any\Drawing.Windows.Forms.xml       contentFiles\any\any\Drawing.xmlcontentFiles\any\any\TextControl.Server.xmlcontentFiles\any\any\TextControl.Windows.Forms.xml   contentFiles\any\any\TextControl.xmllib\net\Barcode.dlllib\net\Barcode.Windows.Forms.dlllib\net\DocumentServer.dlllib\net\DocumentServer.Windows.Forms.Design.dlllib\net\DocumentServer.Windows.Forms.dll       lib\net\Drawing.dlllib\net\Drawing.Windows.Forms.dlllib\net\ImageProvider.dlllib\net\txpdf.dlllib\net\SVGGenerator.dlllib\net\TextControl.dlllib\net\TextControl.Server.dlllib\net\TextControl.Windows.Forms.Design.dlllib\net\TextControl.Windows.Forms.dll       lib\net\bin\tx_css.dlllib\net\bin\tx_doc.dlllib\net\bin\tx_dox.dlllib\net\bin\tx_htm.dlllib\net\bin\tx_pdf.dlllib\net\bin\tx_rtf.dlllib\net\bin\tx_xlx.dlllib\net\bin\tx_xml.dlllib\net\bin\txic.dlllib\net\bin\txkernel.dlllib\net\bin\txtools.dlllib\net\bin64\tx_css.dlllib\net\bin64\tx_doc.dlllib\net\bin64\tx_dox.dlllib\net\bin64\tx_htm.dlllib\net\bin64\tx_pdf.dlllib\net\bin64\tx_rtf.dlllib\net\bin64\tx_xlx.dlllib\net\bin64\tx_xml.dlllib\net\bin64\txic.dlllib\net\bin64\txkernel.dlllib\net\bin64\txtools.dlllib\net\de\Barcode.resources.dlllib\net\de\DocumentServer.resources.dlllib\net\de\DocumentServer.Windows.Forms.Design.resources.dlllib\net\de\Drawing.resources.dlllib\net\de\TextControl.resources.dlllib\net\de\TextControl.Windows.Forms.Design.resources.dll   lib\net\net6.0-windows\TextControl.Windows.Forms.Design.dll lib\net\net6.0-windows\TextControl.Windows.Forms.dll

This is my Package.nuspec file's content:

<?xml version="1.0" encoding="utf-8"?><package><metadata><id>TxTextControl</id><version>1.0.0</version><authors>Me</authors><readme>ReadMe.md</readme><requireLicenseAcceptance>false</requireLicenseAcceptance><license type="expression">MIT</license><description>This is my package description</description><copyright>2024</copyright><tags>TextControl</tags><contentFiles><files include="**\*.xml" buildAction="Content" copyToOutput="true"/></contentFiles></metadata></package>

And this is the build result:

NuGetTest.dllNuGetTest.pdbBarcode.dllBarcode.Windows.Forms.dllBarcode.Windows.Forms.xmlBarcode.xmlDocumentServer.dllDocumentServer.Windows.Forms.Design.dllDocumentServer.Windows.Forms.dllDocumentServer.Windows.Forms.xmlDocumentServer.xmlDrawing.dllDrawing.Windows.Forms.dllDrawing.Windows.Forms.xmlDrawing.xmlImageProvider.dlltxpdf.dllSVGGenerator.dllTextControl.dllTextControl.Server.dllTextControl.Server.xmlTextControl.Windows.Forms.Design.dllTextControl.Windows.Forms.dllTextControl.Windows.Forms.xmlTextControl.xmlde\Barcode.resources.dllde\DocumentServer.resources.dllde\DocumentServer.Windows.Forms.Design.resources.dllde\Drawing.resources.dllde\TextControl.resources.dllde\TextControl.Windows.Forms.Design.resources.dll