that is an interesting hypothetical.
I am far from a rules buff or aficionado, though I'll try and share perspective here.
in either approach, where is the "-10DMG" coming from? EDIT:
Lightsaber Flurry Force Power - make 4 Attacks at -10DMG. thanks for that note hehe.
it's from the custom yoda and a few other recent VSet pieces, gotcha.
the only constraints on Flurry Attack I am aware of are;
-can only attack the same target as the first attack,
-cannot stack with itself, IE, Flurry Attack can't trigger on the critical of a twin attack?
though, of a base attack, a flurry attack
can trigger, leading to a twin...
(-10DMG was from WotC:SWRPG and SAGA, for flurry in that and in the FFG SWRPG)
so, lets consider the following hypothetical;
if your character has say, flurry, impulsive flurry, triple attack, and twin
attack 1 crits - resolve Flurry, which will twin. net 3 attacks
twin from attack 1. twin attacks cannot trigger flurry, so it is only relevant for the damage (auto hit and double damage or whatever modifiers apply on a crit).
Attack 2 doesn't crit,
resolve twin of attack 2. net 5 attacks at this point.
attack 3 crits - resolve flurry, net 7 attacks,
resolve twin of attack 3.
so, even though you have triple attack, flurry and twin,
it is possible to make more than 6 attacks, if the base attack is a critical.
if all 3 base attacks were criticals, you could make up to 10 attacks.
that's more, if the twin attack can trigger a flurry attack too (which thank goodness it cannot).
the odds of natural criticals 3 in a row are slim though.
Use the Force I think also triggers Flurry Attack.
so, you can potentially do a lot of damage, say 130+dmg in a single flurry spree.
it usually burns through force though, it's like a force-fueled version of Attack X + Twin.
I use different colors of dice to discern which attack is a base attack, and which attack is a twin or a flurry.
I remember this being a thing for a Luke that has flurry and use the force from a while back.
at that time, I think EmperorDragon or Sithbot shared a color coded process flow chart of how they resolved it.
I hope this was of some use,
and I look forward to seeing what other folks think about this hypothetical
EDIT:
I think, in light of force power lightsaber flurry granting 4 attacks,
the -10DMG applies to all of those, inclusive of Twins and any Flurry Attacks or things that happen to those.
it'd be after adjusting for a critical doing double damage + modifier.