Here's a table I scribbled down this morning (1D6) to generate the various alliances and enemies each race might have:
6= Symbiotes - these races operate as if one (raise tech level to be the same, this does not raise the tech level of the surrounding races)
5= Allies - these races work well together, fight alongside in wars.
4= Peaceful - while not allies they aren't at war either. Trade between them exists and they are generally friendly towards each other.
3= Peaceful Animosity - the two races aren't at war but generally stay out of each others business, some harbour racist ideas and views against the other.
2= Enemies - while not at war, should the cause arise these two races will be on opposite sides. Racist ideas are more prevelant.
1= At War - these races couldn't be further apart, they are actively fighting each other.
The level of animosity should drop as you move outwards depending upon the reach of the given races. For example two space mastering races at war will be at war everywhere. On the other hand races that only travel within their own system and other nearby systems (within their own sub-sector) will move up the chart by 1 level as you move outwards. If two races were at war within their own sub-sector they would be enemies in neighbouring sub-sectors and have peaceful animosity in neighbouring sectors. It is assumed that any race with a lower tech level than another will automatically treat that race peacefully (4-6), or with peaceful animosity (1-3) because otherwise they would undoubtedly face defeat and near annihilation. You only really need to roll for those races that are on the same tech level and within reach of each other, but you might like to roll to determine if they are peaceful or have animosity toward each other for extra flavour. For example should those two races be in a party together, that could generate friction and drive a plot. Should galactic war break out the roll could determine which races are likely to join which sides and which planets will be on which sides.
In the Aty system, the Iwaperons are treated peacefully by the Nanolin (I rolled a 4), however the Giliseni (1) and the Pir treat them with some suspicion (3). They may fear reprisal as their technology grows.
The Giliseni are treated with suspicion by the Nanolin (1), this is probably due to their apparent dislike for the Iwaperons. (Now for the important roll for the system on the full 1-6 table) The Pir are the same (3), however this is no doubt due to their rivalry with the Giliseni. Finally the Nanolin and the Pir are peaceful (4).
As the universe grows it will no doubt become extremely complicated to track the races and their allies/enemies. I'm going to need a huge sheet of paper and a huge table. Maybe it would be helpful to purchase 3 journals, one to cover the planets, systems, sub-sectors and sectors and the races on those planets. Next one to cover the races in detail, including their various alliances and enemies. Finally one to cover characters which I'll randomly be rolling next. This will lead on to the beginning of a simple story as a band of mercenaries and merchants come together to form my own space faring crew.