My understanding of the limitations on the enemy and ally system only being able to have twenty people on it is that it's expected for the list to be constantly changing. Enter a team arena, ally and enemy the people you need to then when it's done, unally all and unenemy all. Defend a raid, enemy all the raiders, ally all the defenders, then when everything calms down clear your list again.
I dislike this due to how long it takes. I know I am in the minority, playing from my cellphone, but doing this kind of thing manually is the only choice for anyone without much coding experience. It is time consuming and highly irritating. I usually only finish with my enemy and ally lists when people are pulling out, by which time I need to clear them.
I propose there be a way to ally and enemy organisations, like clans, orders, houses and cities.
Even if there are restrictions to how it works, like enemied or allied organisations reset after an hour of non-combat. Or something similar to that. WOuld also make arena much easier of you could just be like ENEMY BLUETEAM and ALLY REDTEAM.
This would make things so much more fluid and easy to use, which is always a good thing, and I can't see any issues that can't be reasonably worked out. This idea is about trying to make thing less about tedious and more fun, help newbies especially and just make this game a better place. Of course, I might be missing something incredibly obvious that might make this a stupid idea. If so, feel free to tear me a new one.