If you are one of my Players: "Sam, Harlan, Simon or Matt" please do not ready this.
I am having the plan to run a side campaign in my World Custom 4e D&D game (Basically skins to replace the races and new names for the classes) This side campaign would consist of my players, making a new set of sub characters who find themselves as new undead creations of a mad scientist who hands them over to his necromancer warlord. This would mean that they would have two parties.
Party A would be their main group they play this the most and it contains characters they have invested time in making a good backstory for.
Party B would be the undead group who only occur if one of my party can't make the session, while also being there to give some behind the scenes on some of the issues in the world e.g. killing a village or attacking a farm etc.
My main concern, is that the players may use this information to meta game or to investigate the enemy when they aren't the main characters. I have spoken to my players about meta-gaming and it shouldn't be a problem, but is there anything I can do to maybe get them invested in that side without them meta gaming, without me being forced to restrict information?
Question
Is there a good way to prevent meta gaming or story conflict through the usage of NPC's characters or the address of the story, so I don't have to restrict their information and make the second part half baked and just bad.