I am not sure, I joined with my friends by them inviting me.
It's strange, it rather sounds like you should.

Here is the easiest way to figure out which friends you can look at squad to try to buy from; go to friends fixtures. Those you see there will be eligible squads, but only if the player in question is between 3 - 5 stars from YOUR perspective. I hope that makes sense, ok? But they have to be on the same server as you to have their players open for negotiation.