Responses

Not that I could see, if I remember right. Typically the spoiler discussion forums tend to be fairly organised and people will use spoiler covers, but like I mentioned, going through it for this series felt somewhat of a chore considering I needed to read everything/most things to find the spoilers I was looking for. I'm pretty sure I would've mentioned it or remembered if I had seen anything about it, but I can only assume it wasn't considered as important to be mentioned? Ofc, feel free to go check out the forum discussions yourself if you want to make sure.
Okay, first of all, just beware that going through the novelupdates forum for this series was kind of a chore, as there is a lot of discussion and deep explanations of some of the early chapters of the novel, and there wasn't really any organised spoilers I tend to see a lot of the time. If you want to go read them yourself, go ahead.
Sidenote: I'm using Yehwa's title of Emperor here, don't be confused, I'm still talking about her.
I found two comments mentioning this, so I'd assume this spoiler is true, but take it with a huge grain of salt, as both commentors mention MTL and reading it from a comment elsewhere. According to the spoiler, this story is using the 3rd life trope.
The "og novel" was their first life. The Emperor felt guilty about Sanya's death, thus we get the whole reincarnation thing.
Second life was in modern Korea. Both the Emperor and Sanya were reborn as a single mother and daughter, but the mother ended up dying first.
We finally get to their third life, which is what we've been following so far. I don't know if the Emperor knows this truth or not. The forum seemed to say that no, the two aren't biologically related in this life.