Today we went through the online form, uploaded all needed documents (hopefully all correct) and paid the €40 fee to the government. Now we need to wait for the approval.
For your information: One person in the department was VERY helpful. Always available when we had questions, helped us all kind of hick-ups. If someone ever needs his details, please email us. It is not his job, but he had done it. Very special thanks to him at this point.