Adjusting for Seven Players (two new)

[Calybos1]

My home-game group has grown to seven players, and I'm looking for the best way to keep things balanced.

Most scenarios are written for a party of four, and the encounters tend to focus on a single bad guy. I don't want to just switch to a higher-CR villain, because the PCs won't be able to affect him or survive his attacks. Plus, I want to make sure everybody has something to do.

Is the best solution just adding in some more lower-level opponents to each combat?

[JohnHawkins]

You will need to increase the number of opponents , adding more minions and possibly adding things like the advanced template and or increasing hp will help.
It depends on how much time you have to put in given you have nearly double the normal group adding another fairly powerful boss to fight alongside the main boss is practical but that will either need designing from scratch or stealing from another encounter.
Another option is to give main bosses 2 actions a turn one at their normal initiative and one say 20 lower which will help with the action economy. I would still add more minions if doing this or increase the hp of the boss a lot