To invitation for a maximum of say, 2 days.

Would ease team formation. Sometimes randoms join fast and screw things up. Only the first player to join/form a team would have this ability.

I  meant public games/tournaments. Obviously, they have to be in Open status.

It' would be a great addition and, thus, has been proposed many times.  Sometimes one more ask gets something on tom's radar, but tweaks like this have been slow coming lately.