I need clarification on the interaction between All Out Assault and Seven Stings Keep.
The way that I (and the others I'd spoken to) assumed it would work is that after you've played All Out Assault you could then bow Seven Stings Keep and name your number as usual, circumventing the drawback of AAO.

Just now, Bayushi Shunsuke said:

I need clarification on the interaction between All Out Assault and Seven Stings Keep.
The way that I (and the others I'd spoken to) assumed it would work is that after you've played All Out Assault you could then bow Seven Stings Keep and name your number as usual, circumventing the drawback of AAO.

If All Out Assault’s effect is active (and players must attack with everyone), a Seven Stings Keep player may name any number—SSK forces them to attack with the named number of characters. This overrides the Assault lasting effect, which both came earlier and is less restrictive than SSK.

[Tyler Parrott, Feb 12 2020]

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I understand there's a ruling with Seven Stings Keep and All out Assault where All out Assault doesn't apply. I'm curious why this is the case, could you provide your reasoning?

In addition, how does Seven Stings Keep interact with Young Warrior? (ex: obtained via Shosuro Actress). For the sake of the discussion, lets assume I have two Young Warriors, and it's the first conflict of the turn. Am I forced to choose a number 2 or higher? If I'm not (and I don't think I should be, based on the All out Assault ruling), and I choose "1", am I forced to use a Young Warrior to attack?

All Out Assault creates a lasting effect that forces each player to declare as many characters as possible as attackers. Seven Stings Keep forces its controller to declare exactly the number of attackers named. If I name 2, I must attack with exactly two characters (SSK) which is also as many characters as I am legally allowed to attack with (AOA). Basically, the more restrictive SSK takes precedence.
Similarly, if you controlled two Young Warriors and triggered SSK naming 1, you would be forced to attack with a single Young Warrior. The other would like to participate, but since you cannot legally declare two attackers one of them has to sit out.

[Tyler Parrott, Mar 17 2020]