Firstly become a Team Leader yourself. You can’t expect anyone to do what you don’t. Let them see what it means to you to be team leader. Show them the benefits.
To motivate them to become team leaders themselves you can re-assign other affiliates with 600VP within the last 90days to your movers or top achievers. Another way that may even work better is to give them new affiliates as they sign up. You can do that with contests or give them shares in your co-op.