In my project the Antarans only have access to the galaxy outside of their Dimensional Pocket System during short periods of time when temporary Dimensional Holes - with random exit points - open within their pocket space.
This is controlled by Python and players are given a popup - warning them about this imminent threat whenever it occurs - and the location of the exit point is shown on the map at the same time.
They are unable to capture systems, working instead like missiles (their units are destroyed after attacking).
Also, the full effect of Quantum Detonators will also be implemented (chance that loosing a battle will cause area damage).