The first idea that never changed in what I wanted to propose is a structure: "War Claim" - requires a formed party.
War claim can only be built adjecent to village claim or closest village banner (which should have their own shields for this or take some of it for themself for siege). For next 8 hours, Attackers have to defend their War claim, after 8 hours, it gets solid, drains 10% of village auth immediatly as it own, to shield itself. Only territory that belongs to the currently sieged banner / village claim, doesn't make attackers leave any scents, on top of that, siege weapons dry a lot faster (after it gets solid, for both sides, only on currently sieged squares). Only people involved in a siege can touch them.
After 8 hours of defending war claim, both sides have ability to call temporary "ceasefire" for next 16 hours (as health issues and in real life time chores calls and other complaints were made due NK or Akihabara siege). This can be called every 24hours but only by one side (counts for both sides).
Sieging party can add shield points to their war claim only by doing damage. For every X points taken from village shield, war claim gains (X/4) of it. Knockingout opponent takes shield equal to damage they have been dealt (capped by max HHP). Killing them, takes 5% of total. There is no scents on the battlefield for both sides. If one goes far too away and starts to attack another square, it counts as normal crime. If a occupied square gets defeated, it joins war claim in terms of territory and attacking group can do on it whatever they wish to do and can select another by placing war banner.
Number of people in siege party must be at best equal to number of flags village has + 2. Example: Village has 8 flag. Maximum numbers of sieging party at time is 8+2 = 10. Expanded for everyday by +2 as reinforcement for both sides, managed on War claim or by Oathing. When siege starts, both sides cannot ADD any new member, until first 24h passed.
When the war claim / village claim is destroyed, the siege ends, giving all attackers a debuff called "veteran of war", preventing them for joining in a siege for next 7 in real days, on top of that, sieging party gets memorized by villagers present at the time, immediatly as red with red icon instead of white kin icon. If sieging party wins and destroy village claim, for next 24 hours they gain complete control over all village territories (private claims included) with all priviliges. Killing heartlings leave scents but taking any stuff or KOing them does not.
There can be multiple war claims put for one village, as to prevent "self-sieging" for never ending protection. Only villages that belong to an realm can preform siege actions against other villages. Each another war claim drains only 50% of value that first war claim gained and also takes 10% of each other war claim for itself. Two war claims can be next to each other, but cannot target the same banner, unless it is village claim. Also doesn't mean it is an alliance between the two, they might fight themselfs as well.
New structure to be able to build only during a siege: Wooden barricade. (10 boards + 10 blocks + metal nugget). The Q of used materials determine how much hits barricade can take (using only tools or hammers, no weapons like sword or fists). People outside of battlefield can't bash it and it's main purpouse is to "close" some areas during ceasefire or slow down enemy progress a very tiny bit.
Roles should make a comeback for this and I know people want to get rid of "shield" mechanic, but It can be just changed to make it work in a better way.
Sorry for text of wall but, it ain't simple and I had been changing the idea everytime I learnt something about siege or PvP. I'm open for discussion to make it as best as possible.
Edit: got few questions so I will give answer here already for everyone:
Q: what if someone who attacks DC?
A: War claim stores a name of people who belongs to it (like village claim)
Q: Purpouse of party is to balance the fight?
A: Pretty much yes, with exception that another group can join the fight for themselfs, putting their own war claim.
Q: How You restrict others from joining up or self-sieging?
A: There can be multiple war claims, as long as another people and villages make them. If group of "another 30 people" want to join up, they put their own war claims and either messes up primary siege group or join them, or fudge both parties and take the glory for themselfs.
Q: So there is not a nice way to have a fair fight?
A: No, unless You organize a special village made up for battleground or something.
Q: Why no scents thou?
A: To let people who have "fair fight" to logout without having their characters killed when just standing out in open. (healthy thing)
Q: How does war claim acts against people outside of the fight?
A: Works the same as any other claim. Restrict movement and actions on it. Also, barricades are there to help with it eventually.