a bit confused atm two chicks that look the same, thought the evil one was there as a collaborated plot with the prince but he doesnt seem to be involved or hiding deep.... future weapons that glock would make anyone a god back then, and the daughter has knowledge of the future..... isekai'ed or reincarnated to the past????? evil chick has obsession with the second prince from a future life perhaps but second prince is going to fall for the good one???? seems interesting.... hope the dots connect well

I think the two are actually the same person. Just my theory, but at some point the "good one" will somehow be sent to the future, then eventually be sent back further into the past and for whatever reason turn against her family and old kingdom.

Of course, they could be two different people, but right now that's the idea I'm operating on. Same person at different points in their life, somehow existing at the same time and fighting on opposite sides of the conflict (or at least with differing goals).

It'd make much more sense if the second Ying were from a parallel world.

Quite the elaborate plan to kill everyone that can recognize her as an imposter.

A few things to note:

All that knowledge to build catapults, trebuchets, grappling hooks and hand axe shows that there was some preparation before heading to the past.

Both the imposter and Ying are connected in some way since it showed a connection between the two when she fell into the jar of water.

The Prince is in cahoots with the imposter while his guards aren't.

I thought it could have been her descendent that looks like her from the future going back to the past instead of having the same person go back and forth in time with added memory wipe to explain her change in allegiance.

Not saying your theory is wrong, maybe the author wants to surprise the audience with such an entangled reveal, but it is a bit convoluted.

oh i c good theory... but would she do her farther in like that if she was the same.... or you think perhaps partial memory loss

thats why i dislike time travel, plot are unpredictable.
but she isnt probably same personn, a parricide is a grave crime and she do it with a smile.