Question on Elemental Ninjutsu lowering resistance's

[Russta]

Does anyone know if you can stack the "resistance downs" of Elemental Ninjutsu? For example, if the renkei is an Explosion I naturally want to use Hyoton to lower Ice resistance for a stronger effect. If I casted, say, Raiton after using Hyoton before it would both the enemies Fire and Water resistance be lowered or just Water because I used it last? Also, roughly how long do they last and is it a diminishing effect?

[Navia]

My belief is only the last element cast sticks, so I keep doing the elemental wheel in order even if I had gone through all the elements once.
I have never ever seen a 'wear off message' from an elemental ninjitsu though, so maybe all the effects stack and the duration if not permanent is longer than being under a curse effect.

[Tifa]

I can't answer your question, but I wonder if it's possible to test this in Ballista by looking at changes in elemental resistance?