im just guessing but dont have high hopes for the other two samurai.
i think the three samurai are the daimyos of the other regions.
we know that oden was the daimyo of kuri, yasuie was the daimyo of hakumai and ushimaru was the daimyo of ringo.
yasuie also stated during his execution that the moment oden was executed, the daimyos of the other regions rebelled against orochi but were put down by kaido.
yasuie said he survived the battle. so its safe to say that ushimaru and the daimyos of kibi and udon regions were taken captive and then executed after the battle.
i think the other two powerful samurais in this chapter will be the daimyos of these two regions.