If you have six companions, you might as well allow 8 or 10 or no cap at all. It's so incredibly over the top in decreasing difficulty, might as well go all in and make it another optional story mode feature. That is the only true optional path, besides making the game scale to your party size automatically. Say, for every new member outside x, enemies have +30% hp, x to hit, x to AC, etc. If it's not either of these two implementations, it seems too late to invest in.
I mean the easiest mode could easily accommodate 5-6 party members without rebalancing the whole game. That makes sense to me. But not higher difficulties... at all. Game is not built for encounters with large parties in the slightest. That would require rebuilding the entire combat experience from the ground up in a span of a few months.
