Splash Damage and Upgrades

If a weapon like say a Battle Hammer with two splash damage upgrade was use with r1 smash, would the splash damage upgrade (24%) stacks with r1's 20%? Or to dumb it down, does splash damage upgrade effect splash damage from smash?

It seems to be that way with dragon blades so I can't imagine why it wouldn't work with a battle hammer.

So how does that work? Normally r1 smash splash is 120% of the player's damage (.2 * 6) when using 2h's. Does that mean you were able to do 140%+ with a dragon blade?