Do Miss Chances Stack?

[shatner]

So I went and re-read Baalz's communion guide and I have one additional question.

Say I have two communions that take place in completely different battles.

Communion 1: You have 2x S1 slaves and 1x W2S1 master. The master casts a W3 spell that costs 40 fatigue. The slaves are effective W1 casters so they should take (40 / 2 x 3) 60 fatigue...

Communion 2: You have 2x S1 slaves and 1x W5S1 master. The master casts a W3 spell that costs 40 fatigue. The slaves are effective W1 casters so they should take (40 / 2 x 3) 60 fatigue... or do they? Since the master is an effective W6, the fatigue cost of the spell should be reduced to a fourth (40 / 4 = 10 fatigue). Does the fact that the master has massive fatigue savings on the spell have any effect on the amount of fatigue the slaves get?