rather then make them not defect, why don't you make rebel/empire leaders just have a very high relationship with the leader? i feel like defecting was very much a part of star wars history, count dooku for example or anakin who did it twice lol. so not allowing lords or commanders to rebel or even flip sides. you could just let us choose a name and a rebel color and allow members of your alliance to join you if you've formed a high enough level and their relationship with their leader has decreased enough. having a high relationship with the leader will mean they won't be willing to deflect until late and only if the leader does things to effect their relationship negatively (if that is a thing this game can do, i don't exactly know how ai relationships work) which if they continued to do things to harm a relationship with someone it would make sense that they would then rebel against right?

because in reading a guide to your mod it mention about how once you take over the other empire you could also rebel. which i never thought about forming my own rebellion rather then just being a part of one. but you're few planets versus a galaxy of people against you just is to hard to accomplish for me lol. but if others joined me it would make it manageable