Master Chief Collection Multiplayer Question

Will the Halo 3 & Halo 4 versions of the MCC connect with the already existing multiplayer for those games on the Xbox 360? In other words, when I boot up Halo 3 or Halo 4, will I be playing with those people on their XboxONE version or is it closed off? I'm just wondering because I don't have an XboxONE yet and if people are going to be playing Halo 3 again I'd like to get back in to it.

I've tried finding the answer elsewhere with no luck so maybe someone here can help. Thanks!