at a guess I'd say that Meeting of Kings would create an instance of the player getting SP = (current SP +4) next turn, but then the Graymas SS would override that with it's own instance of both players getting only 1 SP
Another example would be Nightmare Given Form's open or auto skill. Because it would go after a grim, the new instance would overwrite the Meeting of Kings, because it's not based on lowering the current number, it's based on creating a brand new number.
I haven't tested any of this, it's just what I logically believe to happen, but it would be interesting to test out some of these clashes, including SS that grant +2 sp the next turn, or Gafc, and other effects that lower SP the next turn.
[shameless link] I can still claim I'm a free player cause I haven't spent any of my
money on the game, but instead I used Prizerebel to get my EX packs. Gran Train = viewtopic.php?f=13&t=11761