How to put players on negotiation list?

[Nicolas Vervaeck]

To buy players, there are three options:
1/ auctions = transfer list
2/ negotiation
3/ scout

I still haven't found, how to put my players on the negotiation list instead of the regular transfer list.
Is there a way to do it? Or are there any conditions we should fulfill first?

Thank you!

[tarcanes92]

Train player to within 1 skill point of the next star. Then they are automatically placed on the negotiation list.