Hi! Is it possible to create a service for a package that is not visible as a single seperate service? 

For example: 

Package 1 = service 1 + service 2

But service 1 and 2 are not visible in the services overview.

Thanks! 

Do you mean that you only want to offer a special service that can only be purchased with the package but not as a single service when a customer looks at your catalog or services offered? If this is the case, I believe you can make a separate service  then add this service to the package but not show it on the catalog or service list as an option to purchase, in other words the service can only be obtained if a customer buys the package.  When you publish your catalog and services on a page, you remove or don't show the new service that will only be included in the package or a service that only comes with the package. 

As an after thought, if you did what I mentioned below, the customer may be able to look at the services offer by "Employee" and then it would be visible to where it could be clicked on and purchased. There may be a hide service function that could work with it. I am new to the plugin and not sure if my answer would help or not. I've been reading a lot of documentation about it and watching many of the videos. Good Luck. Let me know how it goes.