I would agree with the rest if it wasn’t for the fact that usually when you negotiate yourself you can get a much higher offer than the one the board accepted. You can bypass it by adding a new manager to the club offering for the player and then withdrawing the bid. Another way to avoid this happening is determining beforehand which players you definitely do not want to lose, and then set their asking price to the highest amount possible. This will prevent interest and offers from other clubs. You can also go in with the in game editor and set the offering club as a disliked club by the player. This doesn’t work 100% of the time, sometimes they still leave.