It is possible to make a group registration in aanmelder.nl. You can activate the option ´group registration ́ in the website settings by clicking on the checkbox. Below registration and website accessibility you will find the text ´extra options´and here you will also find the text ´enable registration and payment of a group of participants by one person´. 
This is the group registration. 

Sequently you have to set the group tickets at payments. Let's say the third person can go to the event with a 50% discount. First of all, you have to set the price for the first two participants. 

Next you click on copy. 
The exact same tickets will appear. In this case the third person has to get 50% discount. 
Available from group registration is now changed to 3 up to 3. The price for a student is now changed in 50% discount( 5 euro) 

At the bottom of the registration form you will find  ́save and add extra person ́. The discount will be shown when the third person has been registered. 

• TIP: Test the group registration in the preview of the registration form for three persons.