Do you mean by sidekick a companion? Sorry english is not my mother language and i just don't got that word.
What i asked was, that if it would be possible to see some king of update, which makes it possible to have all the four companions (controlled by the AI/Computer however you call it). How they enter? Well, in the order that you meeted them up.
About dialogue influence stuff, i don't think this can be mixed up as the companion will only answer when you choose the option that he prefers. If not, i guess they maybe could say what they think about it one by one.
To make it then a bit harder, the difficult should improve a bit when more companions are in the Game.
EDIT: I am not sure if this is possible for a major patch, but i know that Square Enix once allowed a patch for Supcom 2 which was a major patch that changed a majority in the systems.
(the economy remake)