Offline & Online Game Together

I am developing a multiplayer game in UE4. I start by implementing an offline multiplayer game and i am now switching the game to the online multiplayer version. My question is how can i combine these two versions? I want the user to select play offline or online in the main menu. However, while i am switching the online version, i realize that i change all blueprint classes like game mode, game state, player controller etc because in online multiplayer version i need to replicate actors and objects but i don’t need to do this on offline version. I don’t want to duplicate all maps and all blueprints since i don’t want to increase the size of the game. Is there a more convenient and simple way to do this?
Thanks in advance.