Or squeeze in with them and hope they cuddle up!
I think your best solution is to have four couches and/or chairs - that way there will be one left over for you!
It's amazing how much space cats take up, isn't it? My two somehow manage to take up the entire bed.
That is what happened to me this morning. I swear, they were trying to push me off the bed... or only allow me about a foot and half of space on the side of the bed lol.
Awwww. Too many cats on a couch is a good life.
I can now see exactly what the size difference is between Sheamus and his siblings! What a floofball :)