Hello mods! Quick question... if characters after this are able to return to their own worlds and presumably tell everyone at home about it... what would happen if someone were to then later app a castmate?

Like, if Hibiki goes home and immediately dives into the arms of her girlfriend there, how would it work if someone were to then want to app in said-girlfriend later? Would they only be apping from an entirely separate timeline, even if they're both from the same canon point? Or could they potentially app in with knowledge of whatever Hibiki might tell them about the world she's been attached to?

Side-question that isn't as complicated... does cellular communication work between Metaheroes and their home worlds?