RESEARCHSUBJECT_TWIN_FORTRESSES.Entity
to get it you need to add
researchFloatModifiers 1
researchModifier
modifierType "StarBasesPerGravityWellAdjustment"
baseValue 0.000000
perLevelValue 1.000000
Can change it to 100 if you like and have millions of starbases!
Lazy Method simply open up PlayerTechRebel.Entity
add on line 221-222
entityDefName "RESEARCHSUBJECT_HARDENED_DEFENSES"
entityDefName "RESEARCHSUBJECT_TWIN_FORTRESSES"
entityDefName "RESEARCHSUBJECT_FORTRESS_COMPARTMENTALIZATION"
and change count 150 to 153 on line 71
works on Advent and Vasari too