Killing yeast?

I'm trying to do a "quick" mead and backsweeten it with more honey at bottling. The mead has been sitting for about 2 months now, and I've racked off the cake twice now. I'm not worried about clarity so much, since the added honey is going to make it hazy anyways.
I'm not sure if I want to pasteurize the bottles, since I don't know if the heat will affect the flavor of the finished product. Is there a better way to kill off the yeast to ensure they dont start eating away at the added honey? I looked into k sorbate, but that doesnt kill the yeast.. also campden doesnt seem to kill saccromyces either? Thanks.

No. The sulphites/campden stun the yeast and provide enough sulphites so that if there's any malolactic bacteria present they won't munch the sorbate into geraniols.

It's standard practice to stabilise with those two chems and then back sweetening isn't an issue.

Oh and the sorbate prevents the yeast from multiplying further.

Or you could also cold crash for a week or so then rack the chilled mead onto the chems before it warms up for extra security.

Personally I just do a first rack, then stabilise, then back sweeten to my desired level, then clear it with either time or if I want a quicker result I hit the batch with finings.