[Remy]

If 2 alliances are set to Allied in game, then the limit on defense missions gets expanded to include the allied planets. I'm thinking a joint Allied attack page could become available to members of both tags at that point.
If 3 alliances are all set to Allied in game, it becomes a block & a joint block attack page becomes available to members of all 3 alliances.

Will make it possible to have some alliances, (not mentioning any names :P) to avoid the alliance limit and have secundary alliances. If you hardcode defense, then there should be no escape, ever.