Is it somehow possible to have other species as 'sub-colonies' and trade resources with mother colony?
yes it is. you can start a new UE/LIS/Zolarg colony (whichever is different from yours) and ask for annexation by your mother colony through the Transmission Hub as soon as youve unlocked it.
Join Elysion! PNkXQTbj
Join the First Future Federation! discord.gg/fr7sHpt