I made the mistake of starting off Age of Worms with a group of level 5 adventures, who were half way to level 6. I scaled Whispering Cairn as best I could, they still waxed it and I did a little better with Filge.
The rest has taken some explination. So I will go over it. I hope you'll read it and bear with me.
So here we are. Dourstone Mine. They managed to beat Filge into submission and took him as a companion with them. However, I've establishd a small twist, Balabar and his cronies have taken hostage a Barbarian/Fighter/Beastmaster in the group, killed his three animal companions, and left the following note for the group after advising them of what they need to do, to get their friend back.
Hey chumps. I hope your night was rough! I figured it has been about a day since we last spoke and I am quite sure you are ready to begin. You know what is at risk. My comrade Filge is keeping me updated with messages of your lack of progress magically. Every 12 hours that goes by and I have not gotten a positive report from Filge, your mouthy young barbarian friend s being magically drained by a good friend of mine. Chop chop!
I did this part because the Barbarian is actually my sons character he's 8 and basically got in trouble so he was grounded from d&d, and because I feel his character has gotten out of hand, with how much he can handle (it and three animal companions due to beastmaster/wild cohort/bought riding dog) I needed to bring it down so he can start again. When it is all done I am going to leave him back at Barbarian 2/Fighter 2. Keep this in mind, I'll get to it in a moment :).
Now, here is the group as it currently exists.
Level 6 Cleric
Level 6 Rogue
Level 6 Wizard
Level 6 Barbarian (not the one above)
Level 6 Ranger
Level 7 Wizard (Filge after I scaled him)
Out of Party
Level 5 Fighter/Level 1 Stonlord - This character has left while the rest of the party is going to the mine. He is in the Tomb of Zosiel under ground to fulfill his stone lord quest.
Level 2 Barbarian/Level 2 Fighter (the one above)
I read over the scaling and it just isn't going to cut it for this party, I can already see they will blow it away as is and even with the slight incrases the module suggests.
I am going to suprise the rest of the party during the Ebon Aspect fight, when Tordek and Termod (the two out of the party at the moment) return to aid the party in a Last Stand against the aspect. I'm going to explain this turn of events by informing Tordek that his fasting time for stonelord was sped up because the tomb of zosiel has a different effect on time, and when he was finished, since they befriended the rival adventures earlier when they arrived they helped him break termod free.
So that's what I'm dealing with. Filge is going to be tray the party but not until the ebon aspect fight.
Any ideas overall?
The scaling the adventure sidebar might cut it if you had a smaller party but with that many characters it's going to be a challenge.
Perhaps you could take a look at the encounters and rebuild them for a higher CR. By this I mean, the adventure assumes you start at level 3, your group is levels 6 though more likely functioning as level 7 because of party size, so take each encounter and compare it to the assumed APL and then rebuild it at a higher CR. For example, if the adventure is assuming the party will be level 3 and presents a CR 4 encounter that's APL +1. So take that and compare it to your APL of 7 and rebuild the encounter as CR 8 (APL +1).
The major problem that I foresee is that it will be a fair amount of work, especially when you get into rebuilding NPCs like the bulk of Three Faces of Evil will require. Monsters for the most part are easy to swap out with higher CR creatures that are thematically similar.
You could also consider skipping an adventure or two out of the path. Perhaps take some of the core plot points and merge them into a series of encounters that lead to a later adventure, thus getting them on track and minimizing your need to scale up so much. Each adventure has essentially one or two major plot points that advance the rest of the story so you could take just those scenes, scale as needed, and turn them into a single adventure.
After the battle with the overgod you could probably just mash up Encounter at Blackwall Keep and Hall of Harsh Reflections letting you jump back in with Champion's Belt.
Skip Blackwall Keep. It doesn't add much to the story except for Ilthane, and that's an easy fix.
Skip to HOHR after TFOE. You'll have to buff it some.
These are just rough spitball ideas:
As for TFOE, the easiest bet would be replacing the types of creatures.
Instead of Kenku, use Gnolls or Bugbears. Or replace the 'fodder' Kenku with the class leveled Kenku. The acolytes need more levels. Make the allip a wraith or two.
The Grimlocks can be given levels or swapped with Dark Creepers and Dark Stalkers. Or Derro - they're likely to follow a crazy seer.
The Hextor wing can be buffed by Advancing the Beast a couple of hit dice and giving it max hp. Add a few levels to the main NPCs. Leave the cultists alone - they are supposed to suck. They're only purpose is to lead the PCs into the trap. Zombies can be converted to ghouls or wights. This wing is deadly enough though...
I much prefer swapping out creatures than trying to add more low level mooks. They have a crap chance of inflicting damage, and just drag out combat. Better to have something of a challenge.
I also dropped the chokers. And consolidated some of the Grimlock fights. I eliminated the Maze because it struck me as boring. There was a LOT of combat. Its easy to TPK because the encounter areas are close to each other. There are some good ideas on the boards on how to seperate them.
Buff the Overgod as well. Just double his hit dice and max hit hit points and give him a few +'s to hit.