Speaker set up for more than 1 person

What you are asking for is impossible. All your friends will never get good soundstage and centered imagine. The stereo format was not designed for this. That’s its main weakness. Look into multichannel music systems using more than a pair of speakers for that. It goes without saying that the music must be encoded in that particular format. With stereo, the best you can achieve is for two people sitting close together to get decent imaging. The speakers dispersion pattern will dictate how far you can go. DSP systems like BACCH might help. However, the main listening position (MLP) will always be the sweet spot. 

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.