Honestly, Miz, you're comparing apples and pears here.
There is not so much an 'Amarr faction' as an 'Empire faction'. Already when you look at what the 'Khanid Kingdom faction' is doing they are going in quite another direction than the Amarr and it isn't quite easy to integrate both in one unified 'faction'.
So, sure, if you want a 'Minmatar faction' which includes the Minmatar in the Federation, the Republic, the Thukker, and those in the Empire, then you're overreaching, simply put.
Just go for the 'Republic faction', the 'thukker faction' can reasonably be attached just like the 'Khanid faction' is to the 'Empire faction' (and the other way around like many Khanid factionistas will be eager to point out), but there is no unified 'Amarr faction' that includes Amarr that moved to the Federation, Amarr that are Blood Raiders, Amarr that joined the Republic or Amarr thatjoined Ushra'Khan.
Sorry, but you want too much, too hard and in a way that won't work. Don't complain that your task is impossible, if you yourself go around in cricles until you found various ways to make it impossible.
The fact is, there has been a 'Minmatar' or maybe rather 'republican faction' - so it can't be impossible. You're constant clamour that it is impossible and that there is no Matari RP and never will be is rather serving to let shoo people away from such RP. You're shooting yourself in the foot here.
Also,. franky, the level of obsession you have with this is something that I can't rationalize in any way or shape as healthy. To hold onto something when oneself is convinced that it is impossible is quite insane.