Can we store our fleet ships at the Sol starbase or Precursor starbase? Or is buying more ships just like UQM?
In UQM as your alliance grew so did your roster of ships. The ships were only attached to the Vindicator and could not be stored away at the Earth Starbase, not even the Arilou which if I remember correctly you could not actually get more of.
I'm guessing that SC:O does not give you unlimited access to building alien ships at the Earth starbase once you ally, rather you are gifted ships after certain quests or after visiting the alien's starbase. I'm guessing this because quests are so important and also because why would a species openly ally with you against the Scryve instead of slipping you a few of their ships quietly. The Scryve are not busy with the Ur-Quan doctrinal conflict so I think an open alliance would get discovered pretty quickly.