Hypothetically speaking... lets say there was a guardian character with the warden and soresu defender and armorer specs with 4 ranks of defensive stance (critical injury resulting in repulsor fist is responsible for 2 ranks of defensive stance, 1 from the repulsor fist,1 as a "bleeding out" scar talent from AoR forged in battle last page), and another 2 upgrades to incoming attacks from a doubly upgrade sense ongoing effect, with armorer and upgraded deflective armor he's got 3 black dice from armor going into the pool, so against melee attacks from an opponent would be facing 4 red dice and 3 black (at a cost of 4 strain per round).
now with that kind of defensive pool there are good odds of a despair PLUS 3 threat being rolled, which would technically be enough to activate both overbalance (from warden) and parry-improved (from soresu defender)
But here's the question: is it legal to activate both overbalance and parry-improved in response to the same attack. Narratively, it makes sense to me: the guy takes a swing at you, and you hit him back hard enough that you stagger him, but I'm asking about raw.
Like I said, the build is hypothetical, the character is much more likely to be guardian:warden/niman-disciple/exile or warden/niman-disciple/soresu defender, or warden/niman-disciple/shi-cho-knight or warden/niman-disciple/emergent (loving the "force of will" for this character, starting attributes are B3 A3 I2 C3 W3 P2 with all dedications dumped into willpower)
The character concept is shaolin monk meets jedi and before you ask I HAVEN'T SEEN ROGUE ONE YET SO NO SPOILERS and two I'm converting a 4th level d20 RCR character that I originally played in summer 2012, so it is not based off of any character from Rouge One.
niman disciple gives 2 ranks of defensive training which because of the repulsor fist is always active, but the niman-technique, draw closer, force assault combo is just awesome... visualize a jedi/shaolin monk combining telekinesis, kung fu, and a lightsaber yanking an opponent forward who somehow manages to dodge/block the lightsaber strike but the shaolin-monk-styled-jedi connects with an open palm punch (a refluffed force assault move with 1 strength, 2 range, and 1 hurl upgrade) that knocks the opponent back from engaged to medium (or long range), the jedi/shaolin monk stands up straight out of the crouched position, moves his right leg back (the lightsaber is in a reverse grip in his left/forward hand) and using his right hand he motions "come"/"again' to his opponent. That is just an awesome visual for me, and it fits so well with the character that I originally created back in 2012.