Henchmen question: do assist dice numbers decline as group takes damage?

I understand the main henchmen concept - one monster makes the attack for the group each turn, while the others each contribute 1 white assist dice to that attack. So, if you have four monsters in the group, you would add 3 white dice to that attack.

But let's say the group starts with a wound pool of 20.
And after a couple of rounds of battling, that pool is now at 10.

Now that the henchmen are down to half-strength, does that mean the group is only contributing 1 white assist dice per turn? Or do they keep throwing 3 until the entire group is dead?

The white dice will be reduced as henchmen are incapacitated, as the number of dice are added at the creation of the dice pool. Every time a new attack is made the dice pool is created as the base pool + modifiers, and the assistance Fortune die or dice are part of the modifier group.

If you had some sort of reanimation in place, then the dice would be again increased if formerly "dead" henchmen were brought back to life (or unlife, as is probably the case). This is something I have planned for a future encounter in which a necromancer is given a spell which heals any undead units he targets; reanimating models where appropriate.

Your group of henchmen (4 of 5 wounds, something like 4 Gors henchmen) will be only 2 Gors left once they took 10 Wounds. Two of them are in fact dead (or on the ground gasping) and not in the fight anymore. Only 2 remain in the group, 1 Fortune dice bonus only

On my sheet of paper, for henchmen groups i write it like :

Hench Gor I (Soak 7) : 5 / 5 / 5 / 5

and cross them as they go. Visualy easier to count Fortune dice. I put the Damage Reduction too so i don't forget to the armor along with the Toughness)

Where did the soak of 7 come from?

Furlong Doug said:

5 toughness + 2 armor

Yep, Henchmen group still Soak like any other "unit".

A Character hits the Henchmen group for 15 Damage, they mitigate it and take only 15-7=8 wounds. The 1st Henchman drops dead/uncouncious, the second one is wounded and left at 2 (out of 5), the 3rd & 4th are fine. The group only gets 2 Fortunes on attacks now.