i've been always trying to find a way to use them in the game but sadly i couldn't find anything on this site like for exemple there were mods for blueprints for them but they were all taken down and other people just kept asking for their blueprints.
so, i went on an adventure to find a way to use them and i finally found it.
i don't know if this is the right place to post this but whatever for now i just want to help people with the same problem as me
so first go to your starsector folder (of course), then starsector-core/data/world/factions and then open player.faction with notepad++ or just notepad but i recommend notepad++
it might look like there's alot of stuff there but calm down it's pretty easy what you have to do there
press ctrl+F and search for these things:
"knownShips" - important one
optional:
"knownFighters"
"knownWeapons"
"knownHullMods"
under these things you'll see "tags":[],
add this between the "[]"
["derelict", "remnant"] -copy and paste if you must
so it will look like this: "tags":["derelict", "remnant"],
it should be the same for all the other ones
oh and the priority stuff you can do the same too but that means the ai in your faction will prefer to use these ships instead of others (they'll still do use other ones but less frequent)
and well do the same with "shipsWhenImporting"
and you should be good to go
little cheat if you want too:
at the end of the file there will be a thing like: "factionDoctrine" - ctrl+f if you can't somehow find it
that's the stuff you normally see in the command screen, here you can edit all you see there without the limits, like have all your officers be the best, have alot of ships and make the ships almost perfectly - remember this is all for your ai ships from your faction just in case telling ya that
edit at your own risk but it should be pretty easy to pick up and understand
but yeah the important part is up there the last one is your choice really
so good luck making a new ai war out there commander and i'll try to keep in touch incase i missed something or if there's a question and sorry if i made any mistake
oh and a little update the derelict mothership will appear too but the ai won't be able to use it and neither will you it's just invisble and you'll get nothing if you get it through custom production (i didn't test with the other ones yet but i believe it might be the same story, the other one's meaning on the same tab as the mothership)