Some aspects I need help with

[Aigle édenté]

Hello,
there are several issues I need help for :
- I must confirm but it seems that leverages disappear and I can't accumulate them... or is it simply because each are attributed to a specific empire ?
- I don't know how to get war support quickly. The tutorials say I can obtain it with skirmishes, grievances and demands. Is that all ?
- I don't understand how demands work. Like the pic shows I have 3 demands on another empire but nothing happens, he doesn't accept nor refuses them... Isn't he supposed to gave me money ?
https://steamcommunity.com/sharedfiles/filedetails/?id=3322774290
- finally is there some way to see each ennemy's move one by one ? If not I don't understand how reinforcements work and how I can intervene in a conflict opposing my ally to another. Amplitude games seem to work all that way, in Endless space 2 I could'nt either watch ennemies moves and it's frustrating...

[DNLH]

You're correct on Leverage, it's collected against particular Empire and only pooled up together for Congress votes. In general I don't really find Leverage actions all that useful comparing to being able to just sway the votes the way I want (and some actions like lowering War Support can just make war unfun, so I abstain from using them).

War Support and Demands are tied together, you can hover over the bar to see what will cause it to raise or drop (you can see that it will grow by a hefty amount next turn in the screenshot, it's the greyed-out bar that shows the trend). Just generating a grievance gives one-time boost to your War Support, turning it into a Demand will make it generate WS per turn for as long as you have more Demands active than the enemy, until other Empire decides to act on it (either comply or refuse them, giving you in turn a chance to withdraw your demands, generating some final scraps of WS, or declaring war because of them).

Final utility of Demands, they're free of charge when it comes to war and will be granted automatically if you force enemy to Surrender. So if you demand Gold, they're sure to pay it even if it puts them in debt, if you demand Territories, their value will be added to your War Score and they'll be automatically ceded.

I'm not sure about what you mean with the last point. The turns in HK are simultaneous like in their other titles, the ability to give control of your armies to your Ally is a band-aid solution for not being able to help your Allies pretty much at all. That's one thing that really needs more fleshing out before I'll give Amplitude a pass on leaving the game more or less behind them.

[jonnin]

war support is increased in a number of 'odd' ways.
If you have not yet spent time with religion, gaining faith and follwers lets you unlock perks to your civilization and a number of those have powerful effects on war support.
some wonders also affect war support.
some of your civics choices also affect it.
when you combine all that stuff as best you can, winning a battle or forcing the AI (as it often does) to run away gets you a huge chunk of war support and moves your bar quickly towards winning the war.
The ai will make unreasonable demands (like giving it land for nothing) and those stew in the background ginning up war support for them. You want to avoid this by making counter demands or by getting them to back down on the request, and befriending some of them so they are less hostile, etc.

demands: the Ai can accept, reject, or ignore your demands. It rarely accepts them unless you are so much stronger than it as to be just bullying the AI. Ignoring them grants you more war support than rejection, over time.

reinforcements are weird.
if you have an army in range of an ongoing battle, simply moving into the arena will join the fight and you can then add your armies from that stack to the battle, one per round.
Also note that attacking settlements, there are generated from thin air armies that defend it. From the human perspective, the AI's turn is all at once, all the armies move at once or at least one per CPU thread or some such limitation. I would not be astonished if a modern PC could support an AI moving 100+ armies all at once via multithreading... so no, you can't see all that one by one. And this is an issue that some take with the game, that the AI moves and starts battles with advantageous terrain or whatnot in ways the human cannot mimic. On the bright side, turns don't take 30 min for the AI to move one by one...

[Daarkarr0w]

Thanks to both of you DNLH and jonnin for the answer. I will say it provides quite a lot of useful information
I will just add that if you reinforce a battle for the AI, they will take control of your troops and the other way around (if they lend you their troops you will control them).