hoho, there are many changes I would like to change. lets start with the characters. I am perfectly fine with characters having their own stories that connects to a larger plot but we are going to cut characters from the rooster and replace them. Chris, Jake, Helena, and Ada are booted and will be replaced with 2 sets of teams. Leon with Sherry; Rebecca with Piers(He could be a placeholder) Simmons would still be the main villain and Carla(not as an Ada clone) would be secondary villain. We would still use the C-Virus, and they only use to make zombies. They have a slow base form, but they can get stronger in certain situations.
Leon and Sherry
Of course, they would be paired up together, both agents of the US with Simmons as their boss. They are sent into Bioterrorist situation at a fancy hotel, cause by ..lets call them Storm. Leon and Sherry are sent inside to rescue an important person that the government highly values. Simmons is personally overseeing the operation and he is showing a lot of favoritism towards Sherry, while being snide to Leon. They find the person and head on to the roof for pick up, but not before a bossfight with a mutated C-virus creature. Sherry found out that she is immune to the virus, and she is more than willing to make a cure to stop this. Simmons has them both kidnapped by Storm for a in order to keep the cure from being made since she is the only person that they know that is immune, while Leon is subjected to possible torture and isolation. They are rescued when the BSAA found Storm's hideout and conducted a raid. They are after Simmons now since they know that he is behind this. While chasing him, Leon and Sherry would probably meet up with Rebecca and Piers for a bit. I think that Simmons would be obsessed with Sherry as he would be with Ada in the OG plot. For the boss, I think it would involve him being infected and turn him into a spider or a snake. After the fight, they are rescued and with Sherry's blood,was able to make a cure.
Rebecca and Piers
Rebecca is doing research on a new virus that has been cropping up, commissioned by the BSAA for her help. They have been tracking down a major terrorist organization that is using said virus in war torn countries, selling them to be used on people, and turning them into BOWs. Becca has been assign for protection. Piers idolizes Chris Redfield, always thinking that he is a hero and joined the BSAA to be a hero s well. He almost always asks Becca about him, but she tries to tell him that he isn't superman, but a regular human being that has been scarred by Umbrella. Carla is the leader of Storm, and she takes Simmon's orders because she too idolize him, and always wanting his approval at every chance. She tries to kill Becca and Piers, but they escape everytime, which makes her more frustrated. She is also jealous of Sherry since Simmons pays more attention to her. She would be infected by Simmons, turning into a blob monster.
I think that the final boss would come after playing both play through. That Becca and Piers would meet up with Leon and SHerry after defeating Simmons. Blob Carla would follow them, absorbing Simmons to make one giant BOW that they have to team up and defeat once and for all