Jethro made his first suggestion, which was that they must control Steve.
If Big Ivan killed Deyo and Steve at the same time, then there would be nothing to discuss, but if Steve survived, the Organization of Water needed to control him before anyone else.
Although Steve was often by Deyo's side, proximity did not mean inseparability, and as Deyo's finance manager, Steve inevitably had to go out often. So, even if Deyo died, the likelihood of Steve surviving was very high.
Therefore, arrangement in advance was necessary.
Yang Yi had originally planned to sit back and watch the tigers fight, utterly disregarding the conflict between Deyo and Big Ivan, and he thought it wouldn't be too late to make a move after Deyo's death. However, if he needed to arrange things in advance concerning Steve, then he would have to start surveilling Deyo.