At the start of the game, place a Cosmic token on the "1" spot on the Warp's colony tracker. This is how many players can be on the offense when going for win. It's also the number of allies the defense can invite when a player is going for the win.
After the first attempt, should it prove unsuccessful, advance the token to the "2" spot. Now two players can go for a joint win (or still one player alone). And, the defense can invite up to two players to help stop a win.
Repeat each time an attempt fails.
We enjoyed this quite a bit, because players had to lobby the defense to get the invite. Who would send 4 ships (and potentially collect the big rewards)? There was quite a bit of tension each time a player went for the win, because he wasn't necessarily facing a huge defense.
Expansion by Jack Reda and Todd Etter