Speaker set up for more than 1 person

Its completely normal for the sweet spot to move with the listener in a properly set up speaker arrangement. Anything you do to accommodate additional listeners occupying the sofa will compromise the sweet spot for whoever is sitting there. Why not take turns listening when the fellas are over to play hi fi. Personally, I wouldn't want to have to smell them when you're all sitting elbow to elbow!

My main listening room has a single recliner in the sweet spot.  If my girlfriend is over I'll let her sit there and I throw a bean bag chair next to her.    

I agree with Spenav. What you're trying to achieve is fundamentally not possible. A true center image is only possible by one listener sitting precisely between the speakers. Set your speakers and chair up just for one person and then don't tinker with them!

It’s all about compromises with your system.  I would adjust the toe-in or out and go with whichever sounds the best trying several listening positions.  Then move back to where it sounds best when it’s just you.  I put painters tape on the floor to mark the positions so it’s easy to move the speakers’ back and forth as needed.  

Need to know your speakers.