So far, I have been toying with being part of the immortal alliance, as my troops are all "immortal" you could say. Alliances are pretty much welcome, but the SSA is sort of under the control of the DRK, only being let live if they work for them and ship them ABS and troops. The DRK is open to both trade agreements and full-on alliances. The DRK is almost like a super-sentient virus, spreading immortality like a disease. However, while seeming awesome, becoming immortal comes at a price- you lose all of who you were before, and become a super-genius yet are mentally forced to fight for the 'darkness,' or what the super-sentient hive-mind calls itself. During combat, these immortal soldiers will sometimes try to turn the enemy into more of these immortal soldiers, called "darklords." The origins of the empire started a long time ago, much before it was even discovered. Around B.R. 2007, the darklords came together to fight together. Although no one outside of the empire knows where they originated, it is theorized they have existed since the time of the first deadly spaceman. Others believe that it is actually the DSM himself, or a clone of him, that eventually evolved into the superior hive-mind. This is just the tip of the iceberg of background I have thought up for these guys.
to recap: yes, alliances.

I already have a few cameos of the Space Austrians, so battles with them as allies could certainly happen. Other cameos could be arranged, if wanted.