I would like to see the ability to be able to take a break in contrast negotiations for a day or two. Negotiations are never done in one session, taking a break could be good instead of a contract being straight up rejected. Could be used by the player, the footballer, the agent even as a tactic. Like if I try to lowball a player, instead of just rejecting they could say something like "let's revisit these discussions in a few days when you decide to be serious" just to add a bit of realism.
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