Question about package installation via curl

Hi folks, I may have a special challenge regarding the installation of packages via curl command in AEM 6.5 (on prem). There are many posts related to "how to curl", but none fitting to this problem.

We use this shell commands in a script for uploading - and in an later step - installing packages.

curl -u $user:$pwd -F package=@"/${package_name}" -F force=true http://$host:$port/crx/packmgr/service/.json/?cmd=upload 

curl -u $user:$pwd -X POST http://$host:$port/crx/packmgr/service/.json/etc/packages/xxx/<package_name>?cmd=install --progress-bar

This works smooth as butter so far. 

But recently we are working on a new site and the new created package from our development is like a main-package.

By this I mean, we can upload and install this package in the packet-manager via curl, but when I look at the result afterwards, there are 5 more sub-packages, that are NOT installed automatically. These "new" packages have always to be installed manually.

When we upload and install the "main"-package directly in the packet-manager GUI, everything works fine. The sub-packages get unpacked and automatically installed.

Is there a special curl method / parameter to get these unpacked sub-packages also directly installed?