Thank you my friend!
I have made only one reservation for two adults. I have only one reservation code and it is connected with my name. The only thing is that when i press "manage my booking" it doesn't appear the e-ticket number of my friend. I don't think that there is going to be any problem but I just want to be sure!
I have booked on the morning flight.
By the way, you mentioned that you travel fron Amsterdam to Greece often. Is KLM asking for a passport? I don't have one. I just have my ID card which is written in both greek and english characters.

Happy to see that someone speaks my language!!!!!!
Since you wished me "kalo taxidi", I have to answer...
Se euxaristo!!!!